Wireless transmission in shared wireless medium environments

ABSTRACT

Methods, apparatus and systems supporting coexistence of wireless transmission equipment in shared wireless medium environments. The techniques provided herein may be applied to various types of wireless transmission equipment. Under one example, a wireless power transmission system (WPTS) delivers power to wireless power receiver clients via transmission of wireless power signals using one or more frequencies and/or channels within shared wireless medium environments in which other wireless equipment is operating, such as access points and stations in wireless local area networks (WLANs). The WPTS is configured to co-exist with the operations of the other wireless equipment within the shared wireless medium environment by adapting its transmission operations to utilize frequencies or channels that do not interfere with other equipment and/or implementing co-channel and shared channels operations under which access to channels is implemented using standardized WLAN protocols such as PHY and MAC protocols used for 802.11 (Wi-Fi™) networks.

BACKGROUND INFORMATION

The use of wireless communication in today's environments is ubiquitous.It seems that everyone has at least one “smart” wireless device, such asa smart phone or tablet, and many have other types of mobile computingdevices, such as laptops, notebooks, Chromebooks, etc., that supportwireless communication. In addition to cellular and mobile computing,wireless communication technologies are used for other purposes, such asaudio systems, portable telephone systems, screen casting, andpeer-to-peer communication to name a few.

The most common wireless technologies include Wireless Wide AreaNetworks (WWAN) (e.g., LTE, HSPA+, UMTS, GPRS, generally associated withcellular networks), Wireless Local Area Networks (WLAN), includingInstitute of Electrical and Electronics Engineers (IEEE) 802.11a,802.11b, 802.11g, 802.11n, 802.11ac standards (commonly referred to asWi-Fi™ WLANs) and Wireless Personal Area Networks (WPAN), such asBluetooth™. There are also wireless standards such as ZigBee™ that areused for Wireless Sensor Actor Networks (WSAN).

The radio frequency (RF) (radio) bands used by the various wirelessnetworks can be generally classified into two categories: licensed, andunlicensed. Most cellular networks operate in licensed bands, while mostWLANs, WPANs, and WSANs operate using unlicensed bands. Some commonradio bands are collectively referred to as industrial, scientific, andmedical (ISM) bands, which include operations at 2.4 GHz to 2.5 GHz(commonly referred to as 2.4 GHz or 2450 MHz bands), and 5.725 GHz to5.875 GHz (commonly referred to as 5.8 GHz or 5800 MHz bands). ISM bandsgenerally may be used for unlicensed operation, although there are somelicensed users for some of these bands.

Substantially all of the forgoing wireless devices are or can be poweredby rechargeable batteries. Conventional rechargeable battery chargersrequire access to a power source such as an alternating current (AC)power outlet, which may not always be available or convenient. Therehave recently been techniques introduced for so-called “wireless”charging using magnetic or inductive charging-based solutions in whichthe wireless device is placed in close proximity to the charging unit.However, during charging the wireless device must (generally) be placedon the charging base

Wireless power transmission at larger distances often use more advancedmechanisms, such as transmission via radio frequency (RF) signals,ultrasonic transmissions, and laser powering, to name a few, each ofwhich present a number of unique hurdles to commercial success. Wirelesspower transmission systems (WPTS) employing RF signals may utilizeportions of the licensed RF spectrum, including 2.4 GHz and 5 GHz radiobands. This presents a problem when operating in shared wireless mediumenvironments under which other equipment and devices, such as WLANaccess points and stations, are operating using the same or overlappingradio bands. In particular, transmission of wireless power signals insuch shared wireless medium environments may interfere with datatransmissions within WLANs. Accordingly, there is a need for solutionsthat enable a WPTS to coexist with existing equipment when operating inshared wireless medium environments. More generally, transmissions ofsignals using Physical Layers (PHYs) operating the using the same oroverlapping radio bands presents similar problems.

The examples provided herein of some prior or related systems and theirassociated limitations are intended to be illustrative and notexclusive. Other limitations of existing or prior systems will becomeapparent to those of skill in the art upon reading the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same becomesbetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified:

FIG. 1 depicts an example wireless power delivery environmentillustrating wireless power delivery from one or more wireless powertransmission systems to various wireless devices within the wirelesspower delivery environment in accordance with some embodiments;

FIG. 2 depicts a sequence diagram illustrating example operationsbetween a wireless power transmission system and a wireless receiverclient for commencing wireless power delivery in accordance with someembodiments;

FIG. 3 depicts a block diagram illustrating example components of awireless power transmission system in accordance with some embodiments;

FIG. 3A depicts a block diagram illustrating additional components of awireless power transmission system to support augmented IEEE 802.11operations and coexistence with 802.11 WLANs in accordance with someembodiment;

FIG. 4 depicts a block diagram illustrating example components of awireless power receiver client in accordance with some embodiments;

FIGS. 5A and 5B depict diagrams illustrating an example multipathwireless power delivery environment in accordance with some embodiments;

FIG. 6 is a diagram illustrating an example determination of an incidentangle of a wavefront in accordance with some embodiments;

FIG. 7 is a diagram illustrating an example minimum omnidirectionalwavefront angle detector in accordance with some embodiments;

FIG. 8A shows a flowchart illustrating operations and logic forperforming wireless power delivery in a manner that coexists withwireless equipment sharing the wireless medium, according to oneembodiment;

FIG. 8B shows a flowchart illustrating operations and logic forperforming wireless power delivery in a manner that coexists with IEEE802.11 WLANs, according to one embodiment;

FIG. 9A is a diagram illustrating the channel spacing for IEEE 802.11band 802.11g WLANs;

FIG. 9B is diagram illustrating a spectral mask defining the permittedpower distribution across each channel for IEEE 802.11g WLANs.

FIG. 10A is a diagram showing non-overlapping channels for 2.4 GHz WLANsin the United States;

FIG. 10B is a diagram showing non-overlapping channels for 2.4 GHz WLANsin most countries outside of the United States;

FIG. 10C is a diagram showing non-overlapping channels for IEEE 802.11acWLANs;

FIG. 11 is a diagram illustrating an IEEE 802.11 WLAN collisionavoidance mechanism;

FIG. 12 is a diagram illustrating the IEEE 802.11 Request to Send/Clearto Send channel reservation and access algorithm;

FIG. 13 is a diagram illustrating the Distributed Coordination Function(DCF) implemented in IEEE 802.11 WLANs;

FIG. 14 is a table illustrating various parameters relating toimplementing the Distributed Coordination Function using different802.11 PHYs;

FIG. 15 is a diagram illustrating frame formatting implemented for IEEE802.11n at the MAC layer and the PLCP sub-layer, along with how the PLCPProtocol Data Units (PPDU) are transmitted using the IEEE 802.11 DCF;

FIG. 15A is a diagram illustrating a modified implementation of thediagram of FIG. 15A under which time slots selected using the IEEE802.11 PCLP protocol are implemented as WPTS time slots;

FIG. 16 is a diagram illustrating IEEE 802.11 MAC data frame andmanagement frame formats;

FIG. 17 is a diagram illustrating the IEEE 802.11 Frame Control format;

FIG. 18A is diagram illustrating implementation of a WPTS time slotusing an IEEE 802.11b long PLCP PPDU frame structure;

FIG. 18B is diagram illustrating implementation of a WPTS time slotusing an IEEE 802.11b short PLCP PPDU frame structure;

FIG. 19 is a diagram of an exemplary shared wireless medium environmentincluding a WPTS and three WLANs with overlapping coverage areas;

FIG. 20 is a diagram illustrating operations of a multi-PHY host deviceto select and/or reserve time slots for accessing a shared wirelessmedium using a first PHY, and to access the shared wireless mediumduring those time slots using a second PHY;

FIG. 21 is a diagram illustrating three examples of overlappingconditions;

FIG. 22 depicts a block diagram illustrating example components of arepresentative mobile device or tablet computer with one or morewireless power receiver clients in the form of a mobile (or smart) phoneor tablet computer device in accordance with some embodiments; and

FIG. 23 depicts a diagrammatic representation of a machine, in theexample form, of a computer system within which a set of instructions,for causing the machine to perform any one or more of the methodologiesdiscussed herein, may be executed.

DETAILED DESCRIPTION

Embodiments of methods, apparatus and systems supporting coexistence ofwireless transmission equipment in shared wireless medium environmentsare described herein. In the following description, numerous specificdetails are set forth (such as implementation using IEEE 802.11-basedWLANs) to provide a thorough understanding of embodiments of theinvention. One skilled in the relevant art will recognize, however, thatthe invention can be practiced without one or more of the specificdetails, or with other methods, components, materials, etc. In otherinstances, well-known structures, materials, or operations are not shownor described in detail to avoid obscuring aspects of the invention.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” invarious places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments.

For clarity, individual components in the Figures herein may also bereferred to by their labels in the Figures, rather than by a particularreference number. Additionally, reference numbers referring to aparticular type of component (as opposed to a particular component) maybe shown with a reference number followed by “(typ)” meaning “typical.”It will be understood that the configuration of these components will betypical of similar components that may exist but are not shown in thedrawing Figures for simplicity and clarity or otherwise similarcomponents that are not labeled with separate reference numbers.Conversely, “(typ)” is not to be construed as meaning the component,element, etc. is typically used for its disclosed function, implement,purpose, etc.

The terms used in this specification generally have their ordinarymeanings in the art, within the context of the disclosure, and in thespecific context where each term is used. Certain terms that are used todescribe the disclosure are discussed below, or elsewhere in thespecification, to provide additional guidance to the practitionerregarding the description of the disclosure. For convenience, certainterms may be highlighted, for example using italics and/or quotationmarks. The use of highlighting has no influence on the scope and meaningof a term; the scope and meaning of a term is the same, in the samecontext, whether or not it is highlighted. It will be appreciated thatsame thing can be said in more than one way.

Consequently, alternative language and synonyms may be used for any oneor more of the terms discussed herein, nor is any special significanceto be placed upon whether or not a term is elaborated or discussedherein. Synonyms for certain terms are provided. A recital of one ormore synonyms does not exclude the use of other synonyms. The use ofexamples anywhere in this specification, including examples of any termsdiscussed herein, is illustrative only, and is not intended to furtherlimit the scope and meaning of the disclosure or of any exemplifiedterm. Likewise, the disclosure is not limited to various embodimentsgiven in this specification.

Without intent to further limit the scope of the disclosure, examples ofinstruments, apparatus, methods and their related results according tothe embodiments of the present disclosure are given below. Note thattitles or subtitles may be used in the examples for convenience of areader, which in no way should limit the scope of the disclosure. Unlessotherwise defined, all technical and scientific terms used herein havethe same meaning as commonly understood by one of ordinary skill in theart to which this disclosure pertains. In the case of conflict, thepresent document, including definitions, will control.

In accordance with aspects of some embodiments disclosed herein,solutions are provided that enable a wireless power transmission systemto coexist with other equipment operating within a shared wirelessmedium environment. For example, under some embodiments, powertransmission signals employed by a WPTS are transmitted in a manner thatenables the WPTS to coexist with WLAN equipment utilizing one or morechannels in an unlicensed radio band, such as 2.4 GHz, 5 GHz and 5.8 GHzradio bands. However, the teaching and principles disclosed herein arenot limited to WLANs or these radio band, but rather may generally applyto solutions to facilitate coexistence of WPTS equipment in varioustypes of shared wireless medium environments utilizing unlicensed orlicensed radio bands.

Definitions

-   -   Wireless Network: two or more nodes (i.e., wireless-enabled        devices) that communicate wirelessly using RF signals that are        transmitted over a shared wireless media.    -   PHY: Physical Layer used for transmitting signals or associated        protocol operating at the Physical Layer.    -   MAC: Media Access Channel Layer or associated protocol operating        at the MAC Layer.    -   Radio Band: A range of RF frequencies.    -   Channel: A specific radio frequency or radio band used for        wireless transmission.    -   Non-interfering Channel: Channel that uses a frequency band        and/or PHY signaling that is defined or otherwise designed to        not interfere with another channel; includes non-overlapping        channels for IEEE 802.11 WLANs.    -   Co-channel networks: Two or more networks transmitting signals        using the same channel.    -   Co-frequency networks: Two or more networks transmitting signals        using the same frequency and/or operating at channels having        some frequency overlap. This is similar to co-channel networks        except the channel number and width for one PHY used by one        network may be different to the PHY used by another network.    -   Reservation: A time slot reserved by a wireless network node for        transmission over a particular channel.    -   Energy Detect (ED): Detection of RF signal energy level above a        threshold for a particular wireless protocol/standard.    -   Shared Wireless Medium Environment: Environments in which two of        more wireless devices share access to the same channel or        environments including two or more wireless networks having        overlapping coverage areas and operating in the same or similar        radio bands (e.g., 2.4 GHz, 5 GHz, etc.)

The terms “coexist” and “coexistence” in shared wireless mediumenvironments generally mean that equipment being operated in the sharedwireless medium environment do not interfere with the operation of otherwireless equipment that is operating in the environment. Non-interferingoperations may generally be implemented by using a non-overlappingchannel (if available), or implementing a scheme for sharing a channel(i.e., co-channel or co-frequency operation) used by another wirelessnetwork. Another aspect of coexistence relates to the concept of “fair”sharing of the medium, which is applicable when multiple networks sharea channel (sharing between networks) or when multiple devices shareaccess to the same network (e.g., WLAN stations sharing access within aWLAN). (It is noted that when networks in shared wireless mediumenvironments are operating under non-overlapping channels, the aspect offair sharing is met by default, since there is no need to share thechannel.)

To facilitate coexistence in shared wireless medium environments,various wireless standards have been developed, including standardsdeveloped by the IEEE (e.g., IEEE 802.11 standards, IEEE 802.16(WiMAX™), and IEEE 802.15.4 Zigbee™ standard), the Bluetooth SpecialInterest Group (SIG), the 3GPP (3^(rd) Generation Partnership Project),and the European Telecommunications Standards Instituted (ETSI), andothers. Aspects of interoperability of devices implementing the IEEE802.11a, 802.11b, 802.11g, 802.11n, 802.11ac WLAN standards are managedby the Wi-Fi Alliance™, which is a worldwide network of companies thatmanufacture Wi-Fi™ equipment and components.

Additional oversight may also be provided on a country or regional basisby commissions and agencies or the like. For example, in the UnitedStates, the Federal Communication Commission (FCC) has oversight overwireless device operations in both licensed and unlicensed radio bands.With respect to coexistence, the FCC has established rules forunlicensed devices that are designed to prevent harmful interference toauthorized radio services through limits on transmitter power andspurious emissions. The Wi-Fi™ Bluetooth™, and Zigbee™ standards havebeen developed within the framework of these rules, generally with theintention of ensuring cooperative sharing of the spectrum by unlicenseddevices while recognizing that such devices are not protected frominterference.

In addition to the foregoing, the IEEE 802.19 Wireless CoexistenceWorking Group (WG) has been developing standards for coexistence betweenwireless technologies used by unlicensed devices. The IEEE 802.19 WGreviews coexistence assurance (CA) documents produced by working groupsdeveloping new wireless standards for unlicensed devices.

To better understand how to implement a WPTS to coexist in sharedwireless medium environments, an overview of the operation andarchitecture of exemplary WPTS embodiments is now presented.

I. Wireless Power Transmission System Overview/Architecture

FIG. 1 depicts a block diagram including an example wireless powerdelivery environment 100 illustrating wireless power delivery from oneor more wireless power transmission systems (WPTS) 101 a-n (alsoreferred to as “wireless power delivery systems”, “antenna arraysystems” and “wireless chargers”) to various wireless devices 102 a-nwithin the wireless power delivery environment 100, according to someembodiments. More specifically, FIG. 1 illustrates an example wirelesspower delivery environment 100 in which wireless power and/or data canbe delivered to available wireless devices 102 a-102 n having one ormore wireless power receiver clients 103 a-103 n (also referred toherein as “clients” and “wireless power receivers”). The wireless powerreceiver clients are configured to receive and process wireless powerfrom one or more wireless power transmission systems 101 a-101 n.Components of an example wireless power receiver client 103 are shownand discussed in greater detail with reference to FIG. 4.

As shown in the example of FIG. 1, the wireless devices 102 a-102 ninclude mobile phone devices and a wireless game controller. However,the wireless devices 102 a-102 n can be any device or system that needspower and is capable of receiving wireless power via one or moreintegrated power receiver clients 103 a-103 n. As discussed herein, theone or more integrated power receiver clients receive and process powerfrom one or more wireless power transmission systems 101 a-101 n andprovide the power to the wireless devices 102 a-102 n (or internalbatteries of the wireless devices) for operation thereof.

Each wireless power transmission system 101 can include multipleantennas 104 a-n, e.g., an antenna array including hundreds or thousandsof antennas, which are capable of delivering wireless power to wirelessdevices 102. In some embodiments, the antennas are adaptively-phasedradio frequency (RF) antennas. The wireless power transmission system101 is capable of determining the appropriate phases with which todeliver a coherent power transmission signal to the power receiverclients 103. The array is configured to emit a signal (e.g., continuouswave or pulsed power transmission signal) from multiple antennas at aspecific phase relative to each other. It is appreciated that use of theterm “array” does not necessarily limit the antenna array to anyspecific array structure. That is, the antenna array does not need to bestructured in a specific “array” form or geometry. Furthermore, as usedherein he term “array” or “array system” may be used include related andperipheral circuitry for signal generation, reception and transmission,such as radios, digital logic and modems. In some embodiments, thewireless power transmission system 101 can have an embedded Wi-Fi™ hubfor data communications via one or more antennas or transceivers.

The wireless devices 102 can include one or more receive power clients103. As illustrated in the example of FIG. 1, power delivery antennas104 a-104 n are shown. The power delivery antennas 104 a are configuredto provide delivery of wireless radio frequency power in the wirelesspower delivery environment. In some embodiments, one or more of thepower delivery antennas 104 a-104 n can alternatively or additionally beconfigured for data communications in addition to or in lieu of wirelesspower delivery. The one or more data communication antennas areconfigured to send data communications to and receive datacommunications from the power receiver clients 103 a-103 n and/or thewireless devices 102 a-102 n. In some embodiments, the datacommunication antennas can communicate via Bluetooth™, Wi-Fi™ (includingbut not limited to IEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac),ZigBee™, etc. Other data communication protocols are also possible.

Each power receiver client 103 a-103 n includes one or more antennas(not shown) for receiving signals from the wireless power transmissionsystems 101 a-101 n. Likewise, each wireless power transmission system101 a-101 n includes an antenna array having one or more antennas and/orsets of antennas capable of emitting continuous wave or discrete (pulse)signals at specific phases relative to each other. As discussed above,each the wireless power transmission systems 101 a-101 n is capable ofdetermining the appropriate phases for delivering the coherent signalsto the power receiver clients 102 a-102 n. For example, in someembodiments, coherent signals can be determined by computing the complexconjugate of a received beacon (or calibration) signal at each antennaof the array such that the coherent signal is phased for deliveringpower to the particular power receiver client that transmitted thebeacon (or calibration) signal.

Although not illustrated, each component of the environment, e.g.,wireless device, wireless power transmission system, etc., can includecontrol and synchronization mechanisms, e.g., a data communicationsynchronization module. The wireless power transmission systems 101a-101 n can be connected to a power source such as, for example, a poweroutlet or source connecting the wireless power transmission systems to astandard or primary alternating current (AC) power supply in a building.Alternatively, or additionally, one or more of the wireless powertransmission systems 101 a-101 n can be powered by a battery or viaother mechanisms, e.g., solar cells, etc.

The power receiver clients 102 a-102 n and/or the wireless powertransmission systems 101 a-101 n are configured to operate in amultipath wireless power delivery environment. That is, the powerreceiver clients 102 a-102 n and the wireless power transmission systems101 a-101 n are configured to utilize reflective objects 106 such as,for example, walls or other RF reflective obstructions within range totransmit beacon (or calibration) signals and/or receive wireless powerand/or data within the wireless power delivery environment. Thereflective objects 106 can be utilized for multi-directional signalcommunication regardless of whether a blocking object is in the line ofsight between the wireless power transmission system and the powerreceiver client.

As described herein, each wireless device 102 a-102 n can be any systemand/or device, and/or any combination of devices/systems that canestablish a connection with another device, a server and/or othersystems within the example environment 100. In some embodiments, thewireless devices 102 a-102 n include displays or other outputfunctionalities to present data to a user and/or input functionalitiesto receive data from the user. By way of example, a wireless device 102can be, but is not limited to, a video game controller, a serverdesktop, a desktop computer, a computer cluster, a mobile computingdevice such as a notebook, a laptop computer, a handheld computer, amobile phone, a smart phone, a PDA, a Blackberry device, an Androiddevice, an iPhone, and/or a tablet, etc. By way of example and notlimitation, the wireless device 102 can also be any wearable device suchas watches, necklaces, rings or even devices embedded on or within thecustomer. Other examples of a wireless device 102 include, but are notlimited to, safety sensors (e.g., fire or carbon monoxide), electrictoothbrushes, electronic door lock/handles, electric light switchcontroller, electric shavers, etc.

Although not illustrated in the example of FIG. 1, the wireless powertransmission system 101 and the power receiver clients 103 a-103 n caneach include a data communication module for communication via a datachannel. Alternatively, or additionally, the power receiver clients 103a-103 n can direct the wireless devices 102.1-102.n to communicate withthe wireless power transmission system via existing data communicationsmodules. In some embodiments the beacon signal, which is primarilyreferred to herein as a continuous waveform, can alternatively oradditionally take the form of a modulated signal.

FIG. 2 is a sequence diagram 200 illustrating example operations betweena wireless power delivery system (e.g., WPTS 101) and a wireless powerreceiver client (e.g., wireless power receiver client 103) forestablishing wireless power delivery in a multipath wireless powerdelivery, according to an embodiment. Initially, communication isestablished between the wireless power transmission system 101 and thepower receiver client 103. The initial communication can be, forexample, a data communication link that is established via one or moreantennas 104 of the wireless power transmission system 101. Asdiscussed, in some embodiments, one or more of the antennas 104 a-104 ncan be data antennas, wireless power transmission antennas, ordual-purpose data/power antennas. Various information can be exchangedbetween the wireless power transmission system 101 and the wirelesspower receiver client 103 over this data communication channel. Forexample, wireless power signaling can be time sliced among variousclients in a wireless power delivery environment. In such cases, thewireless power transmission system 101 can send beacon scheduleinformation, e.g., Beacon Beat Schedule (BBS) cycle, power cycleinformation, etc., so that the wireless power receiver client 103 knowswhen to transmit (broadcast) its beacon signals and when to listen forpower, etc.

Continuing with the example of FIG. 2, the wireless power transmissionsystem 101 selects one or more wireless power receiver clients forreceiving power and sends the beacon schedule information to the selectpower receiver clients 103. The wireless power transmission system 101can also send power transmission scheduling information so that thepower receiver client 103 knows when to expect (e.g., a window of time)wireless power from the wireless power transmission system. The powerreceiver client 103 then generates a beacon (or calibration) signal andbroadcasts the beacon during an assigned beacon transmission window (ortime slice) indicated by the beacon schedule information, e.g., BeaconBeat Schedule (BBS) cycle. As discussed herein, the wireless powerreceiver client 103 include one or more antennas (or transceivers) whichhave a radiation and reception pattern in three-dimensional spaceproximate to the wireless device 102 in which the power receiver client103 is embedded.

The wireless power transmission system 101 receives the beacon from thepower receiver client 103 and detects and/or otherwise measures thephase (or direction) from which the beacon signal is received atmultiple antennas. The wireless power transmission system 101 thendelivers wireless power to the power receiver client 103 from themultiple antennas 103 based on the detected or measured phase (ordirection) of the received beacon at each of the corresponding antennas.In some embodiments, the wireless power transmission system 101determines the complex conjugate of the measured phase of the beacon anduses the complex conjugate to determine a transmit phase that configuresthe antennas for delivering and/or otherwise directing wireless power tothe power receiver client 103 via the same path over which the beaconsignal was received from the power receiver client 103.

In some embodiments, the wireless power transmission system 101 includesmany antennas; one or more of which are used to deliver power to thepower receiver client 103. The wireless power transmission system 101can detect and/or otherwise determine or measure phases at which thebeacon signals are received at each antenna. The large number ofantennas may result in different phases of the beacon signal beingreceived at each antenna of the wireless power transmission system 101.As discussed above, the wireless power transmission system 101 candetermine the complex conjugate of the beacon signals received at eachantenna. Using the complex conjugates, one or more antennas may emit asignal that takes into account the effects of the large number ofantennas in the wireless power transmission system 101. In other words,the wireless power transmission system 101 can emit a wireless powertransmission signal from the one or more antennas in such a way as tocreate an aggregate signal from the one or more of the antennas thatapproximately recreates the waveform of the beacon in the oppositedirection. Said another way, the wireless power transmission system 101can deliver wireless RF power to the client device via the same pathsover which the beacon signal is received at the wireless powertransmission system 101. These paths can utilize reflective objects 106within the environment. Additionally, the wireless power transmissionsignals can be simultaneously transmitted from the wireless powertransmission system 101 such that the wireless power transmissionsignals collectively match the antenna radiation and reception patternof the client device in a three-dimensional (3D) space proximate to theclient device.

As shown, the beacon (or calibration) signals can be periodicallytransmitted by power receiver clients 103 within the power deliveryenvironment according to, for example, the BBS, so that the wirelesspower transmission system 101 can maintain knowledge and/or otherwisetrack the location of the power receiver clients 103 in the wirelesspower delivery environment. The process of receiving beacon signals froma wireless power receiver client at the wireless power transmissionsystem and, in turn, responding with wireless power directed to thatparticular client is referred to herein as retrodirective wireless powerdelivery.

Furthermore, as discussed herein, wireless power can be delivered inpower cycles defined by power schedule information. A more detailedexample of the signaling required to commence wireless power delivery isdescribed now with reference to FIG. 3.

FIG. 3 is a block diagram illustrating example components of a wirelesspower transmission system 300, in accordance with an embodiment. Asillustrated in the example of FIG. 3, the wireless charger 300 includesa master bus controller (MBC) board and multiple mezzanine boards thatcollectively comprise the antenna array. The MBC includes control logic310, an external data interface (I/F) 315, an external power interface(I/F) 320, a communication block 330 and proxy 340. The mezzanine (orantenna array boards 350) each include multiple antennas 360 a-360 n.Some or all of the components can be omitted in some embodiments.Additional components are also possible. For example, in someembodiments only one of communication block 330 or proxy 340 may beincluded.

The control logic 310 is configured to provide control and intelligenceto the array components. The control logic 310 may comprise one or moreprocessors, FPGAs, memory units, etc., and direct and control thevarious data and power communications. The communication block 330 candirect data communications on a data carrier frequency, such as the basesignal clock for clock synchronization. The data communications can beBluetooth™ Wi-Fi™, ZigBee™, etc., including combinations or variationsthereof. Likewise, the proxy 340 can communicate with clients via datacommunications as discussed herein. The data communications can be, byway of example and not limitation, Bluetooth™, Wi-Fi™ ZigBee™, etc.Other communication protocols are possible.

In some embodiments, the control logic 310 can also facilitate and/orotherwise enable data aggregation for Internet of Things (IoT) devices.In some embodiments, wireless power receiver clients can access, trackand/or otherwise obtain IoT information about the device in which thewireless power receiver client is embedded and provide that IoTinformation to the wireless power transmission system 300 over a dataconnection. This IoT information can be provided to via an external datainterface 315 to a central or cloud-based system (not shown) where thedata can be aggregated, processed, etc. For example, the central systemcan process the data to identify various trends across geographies,wireless power transmission systems, environments, devices, etc. In someembodiments, the aggregated data and or the trend data can be used toimprove operation of the devices via remote updates, etc. Alternatively,or additionally, in some embodiments, the aggregated data can beprovided to third party data consumers. In this manner, the wirelesspower transmission system acts as a Gateway or Enabler for the IoTs. Byway of example and not limitation, the IoT information can includecapabilities of the device in which the wireless power receiver clientis embedded, usage information of the device, power levels of thedevice, information obtained by the device or the wireless powerreceiver client itself, e.g., via sensors, etc.

The external power interface 320 is configured to receive external powerand provide the power to various components. In some embodiments, theexternal power interface 320 may be configured to receive a standardexternal 24 Volt power supply. In other embodiments, the external powerinterface 320 can be, for example, 120/240 Volt AC mains to an embeddedDC power supply which sources the required 12/24/48 Volt DC to providethe power to various components. Alternatively, the external powerinterface could be a DC supply which sources the required 12/24/48 VoltsDC. Alternative configurations are also possible.

In operation, the master bus controller (MBC), which controls thewireless power transmission system 300, receives power from a powersource and is activated. The MBC then activates the proxy antennaelements on the wireless power transmission system and the proxy antennaelements enter a default “discovery” mode to identify available wirelessreceiver clients within range of the wireless power transmission system.When a client is found, the antenna elements on the wireless powertransmission system power on, enumerate, and (optionally) calibrate.

The MBC then generates beacon transmission scheduling information andpower transmission scheduling information during a scheduling process.The scheduling process includes selection of power receiver clients. Forexample, the MBC can select power receiver clients for powertransmission and generate a Beacon Beat Schedule (BBS) cycle and a PowerSchedule (PS) for the selected wireless power receiver clients. Asdiscussed herein, the power receiver clients can be selected based ontheir corresponding properties and/or requirements.

In some embodiments, the MBC can also identify and/or otherwise selectavailable clients that will have their status queried in the ClientQuery Table (CQT). Clients that are placed in the CQT are those on“standby”, e.g., not receiving a charge. The BBS and PS are calculatedbased on vital information about the clients such as, for example,battery status, current activity/usage, how much longer the client hasuntil it runs out of power, priority in terms of usage, etc.

The Proxy AE broadcasts the BBS to all clients. As discussed herein, theBBS indicates when each client should send a beacon. Likewise, the PSindicates when and to which clients the array should send power to andwhen clients should listen for wireless power. Each client startsbroadcasting its beacon and receiving power from the array per the BBSand PS. The Proxy can concurrently query the Client Query Table to checkthe status of other available clients. In some embodiments, a client canonly exist in the BBS or the CQT (e.g., waitlist), but not in both. Theinformation collected in the previous step continuously and/orperiodically updates the BBS cycle and/or the PS.

FIG. 4 is a block diagram illustrating example components of a wirelesspower receiver client, in accordance with some embodiments. Asillustrated in the example of FIG. 4, the receiver 400 includes controllogic 410, battery 420, an IoT control module 425, communication block430 and associated antenna 470, power meter 440, rectifier 450, acombiner 455, beacon signal generator 460, beacon coding unit 462 and anassociated antenna 480, and switch 465 connecting the rectifier 450 orthe beacon signal generator 460 to one or more associated antennas 490a-n. Some or all of the components can be omitted in some embodiments.For example, in some embodiments, the wireless power receiver clientdoes not include its own antennas but instead utilizes and/or otherwiseshares one or more antennas (e.g., Wi-Fi antenna) of the wireless devicein which the wireless power receiver client is embedded. Moreover, insome embodiments, the wireless power receiver client may include asingle antenna that provides data transmission functionality as well aspower/data reception functionality. Additional components are alsopossible.

A combiner 455 receives and combines the received power transmissionsignals from the power transmitter in the event that the receiver 400has more than one antenna. The combiner can be any combiner or dividercircuit that is configured to achieve isolation between the output portswhile maintaining a matched condition. For example, the combiner 455 canbe a Wilkinson Power Divider circuit. The rectifier 450 receives thecombined power transmission signal from the combiner 455, if present,which is fed through the power meter 440 to the battery 420 forcharging. In other embodiments, each antenna's power path can have itsown rectifier 450 and the DC power out of the rectifiers is combinedprior to feeding the power meter 440. The power meter 440 can measurethe received power signal strength and provides the control logic 410with this measurement.

Battery 420 can include protection circuitry and/or monitoringfunctions. Additionally, the battery 420 can include one or morefeatures, including, but not limited to, current limiting, temperatureprotection, over/under voltage alerts and protection, and coulombmonitoring.

The control logic 410 can receive the battery power level from thebattery 420 itself. The control logic 410 may also transmit/receive viathe communication block 430 a data signal on a data carrier frequency,such as the base signal clock for clock synchronization. The beaconsignal generator 460 generates the beacon signal, or calibration signal,transmits the beacon signal using either the antenna 480 or 490 afterthe beacon signal is encoded.

It may be noted that, although the battery 420 is shown as charged by,and providing power to, the receiver 400, the receiver may also receiveits power directly from the rectifier 450. This may be in addition tothe rectifier 450 providing charging current to the battery 420, or inlieu of providing charging. Also, it may be noted that the use ofmultiple antennas is one example of implementation and the structure maybe reduced to one shared antenna.

In some embodiments, the control logic 410 and/or the IoT control module425 can communicate with and/or otherwise derive IoT information fromthe device in which the wireless power receiver client 400 is embedded.Although not shown, in some embodiments, the wireless power receiverclient 400 can have one or more data connections (wired or wireless)with the device in which the wireless power receiver client 400 isembedded over which IoT information can be obtained. Alternatively, oradditionally, IoT information can be determined and/or inferred by thewireless power receiver client 400, e.g., via one or more sensors. Asdiscussed above, the IoT information can include, but is not limited to,information about the capabilities of the device in which the wirelesspower receiver client is embedded, usage information of the device inwhich the wireless power receiver client is embedded, power levels ofthe battery or batteries of the device in which the wireless powerreceiver client is embedded, and/or information obtained or inferred bythe device in which the wireless power receiver client is embedded orthe wireless power receiver client itself, e.g., via sensors, etc.

In some embodiments, a client identifier (ID) module 415 stores a clientID that can uniquely identify the power receiver client in a wirelesspower delivery environment. For example, the ID can be transmitted toone or more wireless power transmission systems when communication isestablished. In some embodiments, power receiver clients may also beable to receive and identify other power receiver clients in a wirelesspower delivery environment based on the client ID.

An optional motion sensor 495 can detect motion and signal the controllogic 410 to act accordingly. For example, a device receiving power mayintegrate motion detection mechanisms such as accelerometers orequivalent mechanisms to detect motion. Once the device detects that itis in motion, it may be assumed that it is being handled by a user, andwould trigger a signal to the array to either to stop transmittingpower, or to lower the power transmitted to the device. In someembodiments, when a device is used in a moving environment like a car,train or plane, the power might only be transmitted intermittently or ata reduced level unless the device is critically low on power.

FIGS. 5A and 5B depict diagrams illustrating an example multipathwireless power delivery environment 500, according to some embodiments.The multipath wireless power delivery environment 500 includes a useroperating a wireless device 502 including one or more wireless powerreceiver clients 503. The wireless device 502 and the one or morewireless power receiver clients 503 can be wireless device 102 of FIG. 1and wireless power receiver client 103 of FIG. 1 or wireless powerreceiver client 400 of FIG. 4, respectively, although alternativeconfigurations are possible. Likewise, wireless power transmissionsystem 501 can be wireless power transmission system 101 FIG. 1 orwireless power transmission system 300 of FIG. 3, although alternativeconfigurations are possible. The multipath wireless power deliveryenvironment 500 includes reflective objects 506 and various absorptiveobjects, e.g., users, or humans, furniture, etc.

Wireless device 502 includes one or more antennas (or transceivers) thathave a radiation and reception pattern 510 in three-dimensional spaceproximate to the wireless device 102. The one or more antennas (ortransceivers) can be wholly or partially included as part of thewireless device 102 and/or the wireless power receiver client (notshown). For example, in some embodiments one or more antennas, e.g.,Wi-Fi, Bluetooth, etc. of the wireless device 502 can be utilized and/orotherwise shared for wireless power reception. As shown in the exampleof FIGS. 5A and 5B, the radiation and reception pattern 510 comprises alobe pattern with a primary lobe and multiple side lobes. Other patternsare also possible.

The wireless device 502 transmits a beacon (or calibration) signal overmultiple paths to the wireless power transmission system 501. Asdiscussed herein, the wireless device 502 transmits the beacon in thedirection of the radiation and reception pattern 510 such that thestrength of the received beacon signal by the wireless powertransmission system, e.g., RSSI, depends on the radiation and receptionpattern 510. For example, beacon signals are not transmitted where thereare nulls in the radiation and reception pattern 510 and beacon signalsare the strongest at the peaks in the radiation and reception pattern510, e.g., peak of the primary lobe. As shown in the example of FIG. 5A,the wireless device 502 transmits beacon signals over five paths P1-P5.Paths P4 and P5 are blocked by reflective and/or absorptive object 506.The wireless power transmission system 501 receives beacon signals ofincreasing strengths via paths P1-P3. The bolder lines indicate strongersignals. In some embodiments the beacon signals are directionallytransmitted in this manner to, for example, avoid unnecessary RF energyexposure to the user.

A fundamental property of antennas is that the receiving pattern(sensitivity as a function of direction) of an antenna when used forreceiving is identical to the far-field radiation pattern of the antennawhen used for transmitting. This is a consequence of the reciprocitytheorem in electromagnetics. As shown in the example of FIGS. 5A and 5B,the radiation and reception pattern 510 is a three-dimensional lobeshape. However, the radiation and reception pattern 510 can be anynumber of shapes depending on the type or types, e.g., horn antennas,simple vertical antenna, etc. used in the antenna design. For example,the radiation and reception pattern 510 can comprise various directivepatterns. Any number of different antenna radiation and receptionpatterns are possible for each of multiple client devices in a wirelesspower delivery environment.

Referring again to FIG. 5A, the wireless power transmission system 501receives the beacon (or calibration) signal via multiple paths P1-P3 atmultiple antennas or transceivers. As shown, paths P2 and P3 are directline of sight paths while path P1 is a non-line of sight path. Once thebeacon (or calibration) signal is received by the wireless powertransmission system 501, the power transmission system 501 processes thebeacon (or calibration) signal to determine one or more receivecharacteristics of the beacon signal at each of the multiple antennas.For example, among other operations, the wireless power transmissionsystem 501 can measure the phases at which the beacon signal is receivedat each of the multiple antennas or transceivers.

The wireless power transmission system 501 processes the one or morereceive characteristics of the beacon signal at each of the multipleantennas to determine or measure one or more wireless power transmitcharacteristics for each of the multiple RF transceivers based on theone or more receive characteristics of the beacon (or calibration)signal as measured at the corresponding antenna or transceiver. By wayof example and not limitation, the wireless power transmitcharacteristics can include phase settings for each antenna ortransceiver, transmission power settings, etc.

As discussed herein, the wireless power transmission system 501determines the wireless power transmit characteristics such that, oncethe antennas or transceivers are configured, the multiple antennas ortransceivers are operable to transit a wireless power signal thatmatches the client radiation and reception pattern in thethree-dimensional space proximate to the client device. FIG. 5Billustrates the wireless power transmission system 501 transmittingwireless power via paths P1-P3 to the wireless device 502.Advantageously, as discussed herein, the wireless power signal matchesthe client radiation and reception pattern 510 in the three-dimensionalspace proximate to the client device. Said another way, the wirelesspower transmission system will transmit the wireless power signals inthe direction in which the wireless power receiver has maximum gain,e.g., will receive the most wireless power. As a result, no signals aresent in directions in which the wireless power receiver cannot receiver,e.g., nulls and blockages. In some embodiments, the wireless powertransmission system 501 measures the RSSI of the received beacon signaland if the beacon is less than a threshold value, the wireless powertransmission system will not send wireless power over that path.

The three paths shown in the example of FIGS. 5A and 5B are illustratedfor simplicity, it is appreciated that any number of paths can beutilized for transmitting power to the wireless device 502 depending on,among other factors, reflective and absorptive objects in the wirelesspower delivery environment.

In retrodirective wireless power delivery environments, wireless powerreceivers generate and send beacon (or calibration) signals that arereceived by an array of antennas of a wireless power transmissionsystem. The beacon signals provide the charger with timing informationfor wireless power transfers, and also indicate directionality of theincoming signal. As discussed herein, this directionality information isemployed when transmitting in order to focus energy (e.g., power wavedelivery) on individual wireless power receiver clients. Additionally,directionality facilitates other applications such as, for example,tracking device movement.

In some embodiments, wireless power receiver clients in a wireless powerdelivery environment are tracked by a wireless power transmission systemusing a three dimensional angle of incidence of an RF signal (at anypolarity) paired with a distance determined by using an RF signalstrength or any other method. As discussed herein, an array of antennascapable of measuring phase (e.g., the wireless power transmission systemarray) can be used to detect a wavefront angle of incidence. A distanceto the wireless power receiver client can be determined based on theangle from multiple array segments. Alternatively, or additionally, thedistance to the wireless power receiver client can be determined basedon power calculations.

In some embodiments, the degree of accuracy in determining the angle ofincidence of an RF signal depends on a size of the array of antennas, anumber of antennas, a number of phase steps, method of phase detection,accuracy of distance measurement method, RF noise level in environment,etc. In some embodiments, users may be asked to agree to a privacypolicy defined by an administrator for tracking their location andmovements within the environment. Furthermore, in some embodiments, thesystem can use the location information to modify the flow ofinformation between devices and optimize the environment. Additionally,the system can track historical wireless device location information anddevelop movement pattern information, profile information, andpreference information.

FIG. 6 is a diagram illustrating an example determination of an incidentangle of a wavefront, according to some embodiments. By way of exampleand not limitation, the incident angle of a wavefront can be determinedusing an array of transducers based on, for example, the received phasemeasurements of four antennas for omnidirectional detection, or threeantennas can be used for detecting the wavefront angle on onehemisphere. In these examples, the transmitting device (i.e., thewireless device) is assumed to be on a line coming from the center ofthe three or more antennas out to infinity. If the at least threedifferent antennas are located a sufficient known distance away and arealso used to determine incident wave angle, then the convergence of thetwo lines plotted from the phase-detecting antennas is the location ofthe device. In the example of FIG. 6,

${\theta = {\sin^{- 1}\left( \frac{\lambda \; \Delta \; \varphi}{2\pi \; s} \right)}},$

where A is the wavelength of the transmitted signal, and Δϕ is the phaseoffset in radians and s is the inter-element spacing of the receivingantennas.

If less than one wavelength of antennas spacing is used between twoantennas, an unambiguous two-dimensional (2D) wavefront angle can bedetermined for a hemisphere. If three antennas are used, an unambiguousthree-dimensional (3D) angle can be determined for a hemisphere. In someembodiments, if a specified number of antennas, e.g., four antennas areused, an unambiguous 3D angle can be determined for a sphere. Forexample, in one implementation, 0.25 to 0.75 wavelength spacing betweenantennas can be used. However, other antenna spacing and parameters maybe used. The antennas described above are omnidirectional antennas whicheach cover all polarities. In some embodiments, in order to provideomnidirectional coverage at every polarity, more antennas may be neededdepending on the antenna type/shape/orientation.

FIG. 7 is a diagram illustrating an example minimum omnidirectionalwavefront angle detector, according to some embodiments. As discussedabove, the distance to the transmitter can be calculated based onreceived power compared to a known power (e.g., the power used totransmit), or utilizing other distance determination techniques. Thedistance to the transmitting device can be combined with an angledetermined from the above-described process to determine devicelocation. In addition, or alternatively, the distance to the transmittercan be measured by any other means, including measuring the differencein signal strength between sent and received signals, sonar, timing ofsignals, etc.

When determining angles of incidence, a number of calculations must beperformed in order to determine receiver directionality. The receiverdirectionality (e.g., the direction from which the beacon signal isreceived) can comprise a phase of the signal as measured at each ofmultiple antennas of an array. In an array with multiple hundreds, oreven thousands, or antenna elements, these calculations may becomeburdensome or take longer to compute than desirable. In order to addressreduce the burden of sampling a single beacon across multiple antennaelements and determining directionality of the wave, a method isproposed that leverages previously calculated values to simplify somereceiver sampling events.

Additionally, in some cases it is extremely beneficial to determine if areceiver within the charging environment, or some other element of theenvironment, is moving or otherwise transitory. Thus, rather than theabove attempt to determine actual or exact location, the utilization ofpre-calculated values may be employed to identify object movement withinthe environment. Each antenna unit automatically and autonomouslycalculates the phase of the incoming beacon. The Antennas (or arepresentative subset of antennas) then report the detected (or measuredphases up to the master controller for analysis). To detect movement,the master controller monitors the detected phases over time, lookingfor a variance to sample for each antenna.

II. Coexistence of WPTS in Shared Wireless Medium Environments

Wireless networks use the concept of a shared wireless medium, where inany radio frequency (RF) region, all of the wireless device share someor all of the same air space. Unlike conventional wired networks, suchas Ethernet (IEEE 802.3), data transmission in wireless networks isinherently broadcast-based, being transmitted in the air as radio waves.This can lead to collisions if more than one device tries to communicatesimultaneously. Wired technologies have techniques for collisiondetection and collision avoidance, such as CSMA/CD (Carrier SenseMultiple Access/Collision Detection) on Ethernet networks. On a wirednetwork, if a collision is detected, packets can be resent. Conversely,in wireless networks there is no way for transmitting devices to detecta collision (with their transmissions) over the air.

Wireless networks use different approaches to address the shared-mediumcollision problem. For example, some wireless networks use a pre-definedtime slot-based approach in combination with multiple channels. Awell-known example of this is a network that employs TDMA(time-divisional multiple access), which is a channel access method forshared-medium networks. TDMA is used in digital 2G cellular networks,such as GSM (Global System for Mobile Communications). It is also usedfor the Digital Enhanced Cordless Telecommunication (DECT) standard forcordless phones. Both GSM and DECT combine TDMA with frequency hoppingto minimize interference. Another scheme is code-division multipleaccess (CDMA), which employs a channel access mechanism. There arevarious flavors of CDMA used in mobile networks, such as IS-95,CDMA2000, wideband CDMA (W-CDMA), TD-CDMA, and TD-SCDMA. LTE (long-termevolution) cellular networks use Orthogonal Frequency DivisionMultiplexing (OFDM), which employs a frequency-division multiplexing(FDM) scheme used as a digital multi-carrier modulation method. OFDM isalso used by some 802.11 standards, such as 802.11a, g, n and ac.

As described in further detail in the following section, WLANs usemechanisms including CSMA/CA (Carrier Sense Multiple Access/CollisionAvoidance) for collision avoidance. Unlike wired Ethernet, WLANsoperations are (generally) half duplex (noting this isn't strictly truefor WLANs using MIMO (multiple input multiple output) radios. This meansa wireless device (AP or endpoint, also referred to a client or“station”) can listen (receive) or talk (transmit), but cannot do bothat the same time. In addition, in any given RF region that containsmultiple wireless devices, only one device can (without interference)transmit at a time. This creates challenges in using RF as a sharedmedium. For instance, because only one device can be transmitting at atime, a single slow device has the potential to slow down all thewireless traffic in that RF region.

A common aspect of each of the foregoing wireless networks is that itsshared medium/collision avoidance scheme is implemented using one ormore standardized wireless protocols specific to the wireless technologyused to implement the network. These standardize protocols are designedto support interoperation with wireless devices from differentmanufacturers. Moreover, many of the protocols support interoperation ofdevices having more advanced capabilities with legacy devices havingreduced capabilities.

In accordance with aspects of embodiments provided herein, method,apparatus, and systems are disclosed for implementing wireless powertransmission schemes over a shared wireless medium that is concurrentlyused for wireless data communications in a coexisting manner. Forexample, the embodiments facilitate wireless power transmission usingthe same RF channels or frequencies within or overlapping the channelsimplemented by existing standardized wireless networks, including WLANsand other wireless networks.

A flowchart 800A illustrating operations and logic for implementing oneembodiment of the approach suitable for various radio bands andassociated standard wireless protocols is shown in FIG. 8A. As depictedby the loops and associated decision blocks and operation blocks, theoperations and logic of flowchart 800A are implemented in an ongoingmanner (noting some of the loops are optional).

In a decision block 802, a determination is made by the wireless powertransmission system to whether any wireless network devices aretransmitting at frequencies and/or channels that may be interfered withby wireless power signal transmissions originating from the WPTS. Tosupport this determination, the WPTS is configured to detect utilizationof one or more standardized wireless protocols over one or more radioband in which the WPTS operates or is capable of operating. For example,if the WPTS operates in the 2.4 GHz radio (or part of the frequenciesused by the WPTS is in the 2.4 GHz radio band), the WPTS will beconfigured to detect standardize wireless protocols that use the 2.4 GHzradio band, such as various versions of IEEE 802.11 (Wi-Fi™) networks.At the same time, the WPTS may also detect operation of wirelesstransmissions using a standardized wireless protocol sharing the same RFregion that are either unlikely to be interfered with by the WPTSoperation or the amount of interference is negligible and/or meetstransmission criteria defined by applicable standardize protocols. Forexample, while DECT equipment utilizes that same RF region as someWi-Fi™ networks, due to the channel-hoping nature of DECT, as well asother considerations, the Wi-Fi™ networks are operated in a manner thatis agnostic to the operations of the DECT equipment. This similarly mayapply to Zigbee™ network, under appropriate conditions.

If the answer to decision block 802 is NO, the logic proceeds to a block804 in which the WPTS transmits wireless power and/or data duringWPTS-selected time periods. Essentially, this means the WPTS operates asif it is the only equipment utilizing the radio band or channel, andthus operates in the manner described above in accordance with FIGS.1-7. As shown by the loop back to decision block 804, during operationin this mode the WPTS will periodically check (e.g., using polling orthe like) to detect any changes in the shared wireless mediumenvironment by re-evaluating the environment the determination made indecision block 802.

If the WPTS detects devices operating in a radio band or frequency thatmay be interfered with, the answer to decision block 802 is YES, and ifthis is the first time the other equipment is detected, the logicproceeds to a block 806 in which the protocol and associated operationalparameters used for the shared wireless medium are identified. Forexample, for wireless protocols employing channels, one or more channels(that are in current use) may be identified. Other operationalparameters may include transmission signal strength. In one embodiment,the WPTS clients (in addition to the WPTS transmitter) may also be usedto detect transmission signal strength and/or operational parameters.For example, many 802.11 clients are enabled to determine an RSSI(Received Signal Strength Indicator) value, which is an indication tohow well the device can “hear” a signal transmitted from an 802.11 AP.In shared medium environments where a WPTS and one or more 802.11 APsare not co-located, the interference that may occur at a client devicemay differ from what might be determined by measurements made at theWPTS transmitter. Accordingly, in this embodiment RSSI measurements byone of more client devices may be used as inputs to how the WPTS will beoperated. Further details for using WPTS clients in connection with WPTSconfiguration are provided below with reference to FIG. 19.

Following the operation of block 806 and for situations where the logichas already flowed through block 806 a first time, the logic nextproceeds to a decision block 808 to determine if there is anon-interfering channel available. For example, some standardizedwireless protocols, such as IEEE 802.11, employ multiple channels underwhich operation at some channels are designed to not interfere withother channels (e.g., non-overlapping channels for 802.11 WLANs). If anon-interfering channel is available, the logic proceeds to a block 810in which the non-interfering channel is selected for use by the WPTS.The logic then returns to block 804, wherein the WPTS operates using thenon-interfering channel.

If there are no non-interfering channels available, the answer todecision block 808 is NO, and the logic proceeds to a block 812 in whichthe wireless power transmitter of the WPTS is operated as an actual oremulated peer wireless network device that implements the protocolidentified in block 806 for transmission access purposes. In furtherdetail, in one embodiment the WPTS transmitter does not fully implementall aspects of the protocol, but rather implements aspects of theprotocol (via emulation of a peer wireless network device) to facilitateaccess to the channel for transmitting power signals and/orcommunicating with the WPTS in a manner that coexists with the operationof other equipment utilizing the shared wireless medium. In otherembodiments, the WPTS transmitter may function as an actual wirelessnetwork device, such as a WLAN access point or station.

Under one embodiment, the WPTS operates as a WLAN access point, such asan 802.11 AP, as described in detail below. Optionally, the WPTS mayoperate as a wireless client device, such an 802.11 station under theprotocol. As yet another option, the WPTS may operate as multiple clientdevices under the protocol, or as a combination of an (actual oremulated) access point and one or more client devices operating overmultiple channels in parallel.

Next, in a block 814, fixed or variable-length time slots are duringwhich broadcasting by the WPTS is to occur are selected or reserved.Generally, such time slots may be dynamical selected or reserved usingrandom access mechanism, or reserved using a standing reservationimplemented by a protocol such as slotted Aloha protocol. Wireless powersignals and/or data is then transmitted by the WPTS to one or more WPTSclients in a block 816 during the time slots. The operations of blocks814 and 816 are then repeated in an ongoing manner, as shown by the loopback from block 816 to block 814.

As shown by the loop from block 816 to 802, the WPTS periodicallyre-evaluates the shared wireless medium environment to detect changes inthe utilization of the radio band(s) it is using for operations. Forexample, another wireless AP located within the signal range of the WPTS(e.g., as defined by a predetermined RSSI threshold) may beginoperating, resulting in a change to the shared wireless mediumenvironment. In addition to wireless APs with fixed location, manymobile phones support wireless “hot spots,” under which they operate asa local 802.11 AP with (generally) reduced range (relative to fixedAPs). In some embodiments, utilization of mobile wireless hot spotswithin the service area of a WPTS are detected, and applicableconfiguration changes are implemented.

Wi-Fi™ CSMA/CA for WPTS Interoperation

In some embodiments, the operations of block 814 will be implemented inaccordance with the applicable wireless protocol that is being employedfor wireless network device operation, and, as such, the determinationof the time slots will be a function of both the protocol and thebehavior of other devices employing the protocol. In some embodiments,one or more IEEE 802.11x protocols are used, wherein ‘x’ can be any of‘a’, ‘b’, ‘g’, ‘n’, ‘ac’, or any other existing or future 802.11protocol defined for use by the Wi-Fi Alliance™, also collectivelyreferred to as Wi-Fi™ networks or WLANs.

Clear and Non-interfering Channel Operations

There are multiple schemes that may be used to support coexistingoperation of a WPTS in a Wi-Fi™ shared medium environment. As discussedabove with reference to decision block 802 of flowchart 800A or FIG. 8A,a first determination is made to determine if there are any wirelessnetworks operating in the shared medium environment that may beinterfered with. In some embodiments, this determination is made using aClear Channel Assessment (CCA) energy detection (ED) measurement.

The original 802.11 requirement for receive sensitivity was to be ableto receive 2 Mbps (using DQPSK) at an RSSI of −80 dBm with a given errorrate. In 802.11a and beyond, the ED threshold was set to 20 dB above theminimum receive sensitivity defined in the applicable standard.

In the original 802.11 (DSSS) standard the ED threshold was defined as:

−80 dBm for stations using a transmit power of 100 mW or more.

−76 dBm for stations using a transmit power of more than 50 mW

−70 dBm for stations using a transmit power of less than or equal to 50mW

In later amendments the threshold was changed to: 802.11b (HR-DSSS): −76dBm, −73 dBm and −70 dBm respectively following the same pattern asdefined for DSSS above; and 802.11a/g/n/ac: −62 dBm (using a 20 MHzChannel).

Vendors will typically implement an ED threshold of just less than −62dBm to be compliant across 802.11 standards. Using an ED threshold of−65 dBm is common. Thus, if the detected energy in the radio band(s)intended to be used by the WPTS is <−65 dBm, all channels (that may beused by the WPTS) are considered clear. ED may also be used for CCAwithin a specific channel, in which case the ED measurement is used todetect whether the channel is idle or in use. Generally, the energydetection measurement is not limited to Wi-Fi™ sources, and my includeenergy detection of non-Wi-Fi™ sources within the radio band(s).

A related aspect of this first scheme is to find a non-interferingchannel that may be used by the WPTS in Wi-Fi™ environments. If anon-interfering channel is available (that is, a channel for which WPTSoperation will meet the channel attenuation requirements per theapplicable 802.11 specification), then that non-interfering channel maybe used.

802.11b, 802.11g, and 802.11n-2.4 utilize the 2.400-2.500 GHz spectrum,while 802.11a, 802.11n, and 802.11ac use the 4.915-5.825 GHz band. Theseare commonly referred to as the “2.4 GHz” and “5 GHz” bands,respectively. Each RF spectrum is sub-divided into channels with acenter frequency and bandwidth, wherein the channels and bandwidthdiffer somewhat between different versions of 802.11.

As an example, FIG. 9A illustrates the channel spacing of an 802.11b and802.11g WLAN operating at (nominally) 2.4 GHz. As shown, the first 13channels begin a 2.412 GHz and have a channel separation of 5 MHz. Thechannel separation between channels 13 and 14 is 12 MHz. As alsodepicted, the channels have a 22 MHz width at −95 dBm, which includes a20 MHz signal bandwidth plus a 2 MHz gap that is used as a guard band.As further depicted in FIG. 9A and FIG. 9B, there is guaranteed channelseparation for channels 1, 6, 11, and 14 (noting the channel separationbetween channels 11 and 14 is less than between 1, 6, and 11).

The non-overlapping channels in the United States for 2.4 GHz WLANs areshown FIG. 10A, while the non-overlapping channels for 2.4 GHz WLAN formost other countries are shown in FIG. 10B. Under IEEE 802.11n, two 20MHz channels can be bounded to form a 40 MHz channel. When using the 40MHz channels, non-overlapping channels are channel 3 for the US andchannels 3 and 11 elsewhere (generally).

There is generally more variance in channel spacing for the 5 GHz WLANoperations, and the channels are not sequentially ordered, as shown inTABLE 1. In this table DFS=Dynamic Frequency Selection; TPC=TransmitPower Control; SRD=Short Range Devices 25 mW max power.

TABLE 1 CHANNEL FREQUENCY EUROPE NORTH NUMBER MHZ (ETSI) AMERICA (FCC)JAPAN  36 5180 Indoors ✓ ✓  40 5200 Indoors ✓ ✓  44 5220 Indoors ✓ ✓  485240 Indoors ✓ ✓  52 5260 Indoors/ DFS DFS/TPC DFS/TPC  56 5280 Indoors/DFS DFS/TPC DFS/TPC  60 5300 Indoors/ DFS DFS/TPC DFS/TPC  64 5320Indoors/ DFS DFS/TPC DFS/TPC 100 5500 DFS/TPC DFS DFS/TPC 104 5520DFS/TPC DFS DFS/TPC 108 5540 DFS/TPC DFS DFS/TPC 112 5560 DFS/TPC DFSDFS/TPC 116 5580 DFS/TPC DFS DFS/TPC 120 5600 DFS/TPC No Access DFS/TPC124 5620 DFS/TPC No Access DFS/TPC 128 5640 DFS/TPC No Access DFS/TPC132 5660 DFS/TPC DFS DFS/TPC 136 5680 DFS/TPC DFS DFS/TPC 140 5700DFS/TPC DFS DFS/TPC 149 5745 SRD ✓ No Access 153 5765 SRD ✓ No Access157 5785 SRD ✓ No Access 161 5805 SRD ✓ No Access 165 5825 SRD ✓ NoAccess

With respect to channel overlap for 5 GHz operations, different channelsmay have different channel widths. For example, 802.11ac may usechannels having widths of 20 MHz (channels 36, 40, 44, 48, 52, 56, 60,64, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, 144, 149,153, 161, 165, 169) 40 MHz (channels 38, 46, 54, 62, 102, 110, 118, 126,134, 142, 151, 159), 80 MHz (channels 42, 58, 106, 122, 138, 155), and160 MHz (channels 50, 114). FIG. 10C shows the non-overlapping 40 MHzand 80 MHz 802.11ac channels.

In addition to specifying the channel center frequency, 802.11 alsospecifies (in Clause 17) a spectral mask defining the permitted powerdistribution across each channel, as shown in FIG. 9B for 802.11g. Themask requires the signal be attenuated a minimum of 20 dB from its peakamplitude at ±11 MHz from the center frequency, the point at which achannel is effectively 22 MHz wide. The result of this is thatadditional channels that are (nominally) overlapping may be used whilemeeting the attenuation requirements if the signal strength of the otherchannels is low enough. For instance, it may be possible to use channels1 and 3 or 1 and 4 and meet the minimum attenuation requirements if thedevices using channels 1 and 3 or 4 are spaced far enough apart. Inaccordance with decision block 808 and block 810 of flowchart 800A,detection and selection of a non-interfering channel may involve signalstrength measurements at one or more locations in the shared wirelessmedium environment.

Wi-Fi™ CSMA/CA for WPTS Coexistence

Under Some Environments, a Non-Interfering Channel May not be Available.Alternatively, in other environments utilization of non-interferingchannels may not be an option, as it might violate an IT policy or forother reasons. To address these situations, in some embodiments an802.11 CSMA/CA scheme may be used. The 802.11 CSMA/CA schemes includeCCA—Carrier Sense (CS)—PLCP Preamble, and CCA—MAC—Duration/ID and theNetwork Allocation Vector (NAV). Under CCA—Carrier Sense (CS)—PLCPPreamble, a PLCP (Physical Layer Convergence Procedure) header is usedto transmit how much time is needed to transmit the data. This may besent as a coding method and bytes or simply in microseconds (μS), but isgenerally sent at the lowest default mode. 6 Mbps at a signal level of−82 dBm is the minimum required receive sensitivity to meet the minimumrequired 802.11 standards. However, enterprise WLAN equipment havereceiver sensitivities that are vastly better than this required value.For example, some WLAN equipment go lower than −95 dBm.

Aspects of CCA-MAC—Duration/ID and the Network Allocation Vector areillustrated in various Figures herein and described in detail below.Under this approach, a Duration or Duration ID indicates future trafficto allow for interframe spaces, ACKs, etc., and allows for completeframe transmission without interruption. The MAC header may also be sentat higher rate and/or at a different rate than the data that follows.

As discussed above, Wi-Fi™ stations cannot detect collisions over theair. To address this, IEEE 802.11 protocol define a “randomized access”medium contention approach. Technically, this is called p-persistentCSMA, where “p” indicates the probability of transmission when themedium is found to be idle after it was previously busy (perhaps due toa previous frame transmission). Randomized network access is beneficialwhen multiple stations have queued traffic awaiting transmission, yetthe medium is busy. The previous frame transmission and access deferralserve to align subsequent transmission attempts by multiple stations,and without randomized access, there is a much higher probability offrame collisions. Coupled with the inability to detect collisions overthe air, multiple stations would continue transmitting at the same timefor the full length of the frame, wasting large amounts of airtime andcausing significant network overhead.

Wi-Fi™ collision avoidance mechanisms include inter-frame spacing fordifferent high-level frame types (for instance, control versus dataframes) and a contention window to introduce randomness into thedistributed medium contention logic of radio transmitters since there isno central source of coordination between Wi-Fi™ stations. Aspects ofthis scheme are depicted in FIG. 11.

In a manner similar to Ethernet, Wi-Fi™ WLANs transfer data via packetsencapsulated in frames. Inter-frame spacing provides priority access fora select few types of control frames necessary for proper networkoperation. The Short InterFrame Spacing (SIFS) value is used foracknowledgements that must directly follow the previous data frame;Distributed Coordination Function (DCF) InterFrame Spacing (DIFS) isused for non-QoS (Quality of Service) data frames; Arbitrated InterFrameSpacing (AIFS) is used for QoS data frames and is variable based on theWi-Fi™ Multimedia (WMM) Access Category (AC) to which the frame isassigned.

Before frame transmission, Wi-Fi™ stations select a random timer valuewithin the contention window range and countdown until the timer expires(unless the medium was idle immediately prior, in which case thecontention window timer may be skipped). Only then are stations allowedto transmit the frame if the medium is still idle. If a collision occurs(as implied by the absence of an acknowledgement frame), then thetransmitting stations double the contention window size to reduce theprobability of a subsequent collision, up to a fixed maximum contentionwindow size. This is called Truncated Binary Exponential Backoff. Theinitial small contention window size is referred to as the ContentionWindow Minimum (CWMin) and the capped maximum size is referred to asContention Window Maximum (CWMax). When WMIM QoS is in use, bothinter-frame spacing and the contention window size vary based on theWMIM AC to which the frame belongs, providing a statistical advantagefor higher priority traffic over lower priority traffic. This method ofprobability-based medium contention introduces a large amount of networkoverhead to minimize the possibility of a frame collision.

Since Wi-Fi™ stations cannot directly detect collisions over the air andbecause the medium is not reliable, which can result in frame loss orcorruption due to various sources of signal attenuation or RFinterference, various version of the 802.11 protocol specify use ofpositive frame acknowledgments. Under this scheme, the receiving stationsends back a short acknowledgment frame to the transmitting station,indicating successful reception of the immediately preceding data frame.However, since there is an acknowledgement for each transmission,positive frame acknowledgement is a large source of network overhead onWi-Fi™ networks. 802.11n and 802.11ac stations can minimize both mediumcontention and acknowledgement overhead by using frame aggregation andblock acknowledgements, which allow the transmitting station to sendmultiple data frames at once and receive one acknowledgement from thereceiver. By eliminating the need to acknowledge each individual frame,more network capacity is available for data transmission, resulting inbetter system performance. This is due, in part, to the half-duplexnature of 802.11, which relies on the same channel (frequency) forbi-directional communication. The block acknowledgement indicates whichframes were received successfully and which were not, allowing selectiveretransmission of only the frames that were not properly received(similar to TCP selective acknowledgements at Layer 4 in the OSI model).

Operation Supporting Legacy WLAN Stations

802.11 specifies protection mechanisms that provide backwardscompatibility to ensure the coexistence of older WLAN stations withnewer ones as well as to ensure all Wi-Fi™ stations on the channel aremade aware of a pending frame transmission and defer access to preventframe collisions, reducing hidden node problems. Such backwardscompatibility is necessary because stations that only implement earlier802.11 protocols (e.g., 802.11a and 802.11b) cannot interprettransmission at higher data rates by stations implementing more recent802.11 protocols (e.g., 802.11g, n, or ac) due to different modulationand encoding techniques. Therefore, newer stations need to transmitRTS/CTS (Request to Send/Clear to Send) or CTS-to-Self control frames atthe legacy data rate before transmitting their higher-speed data frames.RTS/CTS ensures that all stations receive the frame and appropriatelyset their NAV (which is a type of internal back-off timer) to defertransmission for the length of time indicated for completion of thesubsequent higher-speed data frame transmission. The use of the NAVsupports Virtual Carrier Sense under which the other stations areenabled to determine how much time the channel will be busy followingthe RTS/CTS exchange.

Most modern 802.11 stations automatically implement CTS-to-Selfmechanisms for protection when the AP indicates that older stations areassociated or detected within range. Generally, RTS/CTS must be manuallyenabled, but is more thorough in protecting a frame transmission fromcollision because it prevents hidden node issues and allows all stationswithin the AP range to hear the CTS frame when it is transmitted by theAP. As illustrated in flowchart 800B of FIG. 8B and described below,RTS/CTS will be used by a WPTS to provide legacy support, if needed, or,alternatively, may be selectively activated.

The foregoing operations are schematically illustrated in diagram 1200of FIG. 12. Diagram 1200 depicts operations performed by a source(transmitter) 1202, a destination (receiver) 1204, and other stations1206. The sequence starts with source 1202 detecting an idle channel,followed by transmitting a request to send (RTS) frame 1208. The RTSframe contains five fields, including a frame control, duration,receiver address (RA), transmitter address (TA), and frame checksequence (FCS). The TA identifies source 1202 as the stationtransmitting the RTS and the RA identifies destination 1204 as thestation to which the data (to be sent) following the RTS/CTS sequence isdestined. After the RTS message has been transmitted, a first SIFSperiod 1210 occurs, followed by destination 1204 returning a clear tosend (CTS) frame 1212 to source 1202. The CTS frame includes a framecontrol, duration, RA, and FCS.

Meanwhile, operations are performed by the other stations in parallel.As discussed above, the RTS frame 1208 includes a duration, whichcorresponds to a timeframe during which the shared medium will be inuse. Accordingly, a NAV (RTS) 1214 is generated for each of the otherstations 1206. Similarly, a NAV (CTS) 1216 is generated upon completionof the CTS frame 1212.

Returning to the operations of source 1202 and destination 1204, source1202 transmits a DATA frame 1218 following a second SIFS period 1220.Details of various 802.11 data frame formats are discussed below. DATAframe 1218 includes various fields (discussed below in further detail)including a data (payload) field containing the data being transmittedto destination 1204. Following transmission of DATA frame 1218 is athird SIFS period, followed by an acknowledgment (ACK) frame 1224returned by destination 1204 to source 1202.

As illustrated, the end of NAV (RTS) 1214, NAV (CTS) 1216, and ACK frame1224 are configured to coincide in time. In practice, each of the otherstations implements a countdown timer that is set to an initial countvalue corresponding to the durations fields of RTS frame 1208 and CTSframe 1212, respectively. At the expiration of the countdown time, eachof the other stations 1206 listen for an idle medium during a DIFSperiod 1226. Subsequently, a random channel access with backoff isimplemented followed by transmission of a DATA frame 1228.

Distribute Coordination Function

An illustration of the Distributed Coordination Function (DCF) used by802.11 WLANs is shown in FIG. 13. The transmission cycle of DCF(T_(DCF)) consists of DIFS time (T_(DIFS)), backoff time (T_(B)), datatransmission time (T_(DATA)), SIFS time (T_(SIFS)) and ACK transmissiontime (T_(ACK)):

T _(DCF) =T _(DIFS) +T _(B) +T _(DATA) +T _(SIFS) +T _(ACK)  (1)

The backoff time TB is a function of a random*time slot with binaryexponential backoff:

$\begin{matrix}{\frac{1}{N + 1}{\sum\limits_{i = 0}^{N}i}} & (2)\end{matrix}$

Examples of various values for SIFS, Slot Time, PIFS, and DIFS fordifferent 802.11b, 802.11g, 802.11a, and 802.11n PHY (Physical) layersare shown in FIG. 12. Under 802.11 embodiments disclosed herein, thebackoff time that is to be implemented will be a function of theapplicable 802.11 PHY that is detected (e.g., detected in block 806 offlowchart 800).

The upper portion of FIG. 15 depicts an IEEE 802.11n MAC frame format,which includes a MAC Protocol Data Unit (MPDU) 1500 at the MAC layer.MPDU 1500 includes a MAC header 1502, a payload 1504 having a size of0-2312 Bytes, and a 4-Byte Frame Control Sequence (FCS) 1506. MAC header1502 comprises a 2-octet frame control field, a 2-octetDuration/connection ID field, three 6-octet (48-bit) addresses fields, a2-octet sequence control field, a fourth 6-octet address field, a2-octet QoS control field, a 2-octet HT control field.

The 802.11 PHY is divided into two sublayers

-   -   1. PLCP (Physical Layer Convergence Procedure) sublayer    -   2. PMD (Physical Medium Dependent) sublayer        The PLCP sublayer prepares the frame for transmission by taking        the frame from the MAC layer and creating a PLCP Protocol Data        Unit (PPDU) 1508. The PMD sublayer (not shown) then modulates        and transmits the data as bits. When the MPDU 1500 is handed        down to the physical layer it is referred to as PLCP Service        Data Unit (PSDU) 1510. When PLCP receives the PSDU, it prepares        the PSDU to be transmitted and creates the PPDU. The PLCP        sublayer also adds a preamble and PHY header to the PSDU        (collectively depicted as PLCP header 1512). The PLCP header        includes a 4-bit RATE field defining a transmission rate to be        used, a 1-bit reserved field, a 12-bit length (LEN) field        defining a length in bytes of the transmission (to follow), a        1-bit parity field, a 6-bit tail, and a 16-bit service (SERV)        field. Based on the rate and the length information,        802.11a/g/n/ac receiving stations can determine how long the        channel will be busy.

For stations using legacy DSSS (802.11) and HR-DSSS (802.11b) radios,the PLCP Header is preceded by a Start of Frame Delimiter of 16 bits(not shown in FIG. 15). The DSSS/HR-DSSS PLCP Header contains a LengthField defining the period of time in microseconds that the channel willbe busy for (as opposed to the length in bytes uses by 802.11a/g/n/acstations).

The lower portion of FIG. 15 shows how a PPDU is sent using theDistributed Coordination Function. As illustrated, the transmissionsequence begins with a DIFS period 1514, followed by a variable backoff(BO) 1516. A transmit preamble 1518 is then broadcast, followed by asignal 1520 composed of one OFDM symbol. Signal 1520 includes all of thefields in the PLCP header 1512 except for the service field. Data 1522is then transmitted, which will use a variable number of OFDM symbols,with the number of symbols being a function of the amount of payloaddata 1504. As further shown, data 1522 is composed of the 16-bit servicefield, PSDU 1510, the 6-bit tail, and any padding. After data 1522 istransmitted, the medium is idle for a SIFS period 1524, followed by anACK frame 1524. This sequence is then repeated in an ongoing manner.

In some embodiments the WPTS transmitter operates as an emulated 802.11access point and the WPTS transmitter and clients access the sharedwireless media during time slots that are identified (selected orreserved) using the applicable 802.11 protocol version. For example, asshown in FIG. 15A, the WPTS transmitter is operating under the 802.11nprotocol to obtain access to the channel. In other embodiments, the WPTStransmitter operates as an actual 802.11 access point that is augmentedto support the additional functionality disclosed herein. For example, aWPTS transmitter may operate as a Wi-Fi™ access point for communicatingwith WPTS client systems in the manner discussed above, with referenceto communication block 330 of FIG. 3A, discussed below.

As illustrated, the timing diagrams and layers are similar in FIGS. 15and 15A, including the PLCP sub-layer and the use of the DistributedCoordination Function. The portions of the timing diagram shown in grayin FIG. 15A indicate the WPTS is operating under the 802.11n protocol inthe conventional manner. However during the period data 1522 would betransmitted under the 802.11n protocol shown in FIG. 15, the WPTS hasaccess to the shared wireless medium, as depicted by a WPTS time slot1550 in FIG. 15A.

During a WPTS time slot, the WPTS has access to the channel (orutilizing frequencies within or overlapping the channel) and can utilizethe time slot for WPTS purposes. During a given WPTS time slot, the WPTSmay transmit power signals to the WPTS clients using the WPTStransmission scheme discussed above. In addition, the WPTS may also senddata to the WPTS clients and/or receive data from the WPTS clientsduring a WPTS time slot. For example, a given WPTS time slot may entaila pair of communications between a WPTS transmitter and a WPTS client(e.g., used for WPTS operations), followed by transmission of powertransmission signals during the remainder of the WPTS time slot, or theorder may be reversed, where the power transmission signals aretransmitted during the first portion of the WPTS time slot.

The foregoing operations are different than conventional 802.11operation in several respects. First, under conventional 802.11operations, a WPTS client (operating as a WLAN station) could onlytransmit during a time slot selected or reserved by the WPTS clientusing the applicable 802.11 protocol. Second, during a WPTS time slot,the WPTS transmitter may transmit power signals during the time slotwithout following the PLCP sublayer format of a 16-bit service field,followed by PSDU 1510, and then followed by a tail and a pad (i.e., anypadding). Rather, the entire time slot may be used by the WPTS for WPTSpurposes.

As another augmentation to conventional 802.11 operation, when apositive acknowledgment scheme is being implemented for 802.11communications, there is no need to acknowledge the WPTS power signals.As a result, the WPTS time slot can be extended to use any following(the transmission of data) time allocated for the channel for positiveACKs.

FIG. 16 shows examples of an 802.11 MAC data frame format 1600 and MACmanagement frame format 1602. For 802.11a/b/g, the MAC header for thedata frame includes a frame control field, Duration/connection ID field,three address fields, a sequence control field, fourth address field,and a QoS control field. The MAC header for the 802.11a/b/g managementframe includes a frame control field, a Duration field, three addressfields, and a sequence control field. As shown, the MAC headers for eachof the data frame and management frame formats for 802.11n furtherincludes a 4-octet HT control field.

FIG. 17 shows further details of the frame control field 1700 of an802.11 frame. The fields/flags include a 2-bit protocol version field1702, a 2-bit frame type field 1704, a 4-bit frame sub-type field 1706,a ToDS bit 1708, a FromDS bit 1710, a more fragments bit 1712, a retrybit 1714, a power management flag 1716, a more data bit 1718, a 1-bitsecurity bit 1720, and a reserved field bit 1722.

FIGS. 18A and 18B respectively illustrate the long and short PLCP PPDUframe structures for 802.11b WLANs. Under the long PLCP PPDU framestructure of FIG. 18A, the PLCP preamble is 144 bits, and the PLCPheader is 48 bits, followed by a variable-length PSDU. The short PLCPPPDU frame structure has a PLCP preamble of 72 bits with the same 48-bitPLCP header as the long PLCP PPDU frame structure. Under both framestructures, the preambles are transmitted at 1 Mbits/s and the PLCPheaders are transmitted at 2 Mbits/s. Under the long PLCP PPDU framestructure, the PSDU can be transferred at 1, 2, 5.5, or 11 Mbits/s. Forthe short PLCP PPDU frame structure, the PSDU can be transferred at 2,5.5, or 11 Mbits/s.

FIG. 8B shows a flowchart 800B that may be used by a WPTS to supportcoexistence in shared wireless medium environments including one or more802.11 WLANs, according to some embodiments. Generally, some of theoperations of flowchart 800B may be implemented in associated operationsin flowchart 800A described above and illustrated in FIG. 8A.

In a block 850, ED is used to detect the existence of any WLANsoperating within the wireless environment used by the WPTS (i.e., withinthe WPTS operational environment). The operation of block 850 may alsobe performed periodically to detect changes to the WPTS operationalenvironment, such as to detect the addition or removal of a WLAN withinthe WPTS operational environment. If one or more WLANs are detectedwithin the frequency range the WPTS may utilized for transmittingwireless power signals, then the WPTS operational environment is ashared wireless media environment (i.e., the wireless media (airspace)is being shared by multiple wireless systems and/or networks.)

Presuming one or more WLANs are detected, the WLAN MAC/PHY protocol andchannel is identified for each WLAN that is detected, as depicted bystart and end blocks 851 and 852, and the operations of block 854. Next,in a decision block 856, a determination is made to whether there areany non-overlapping channels available. More specifically, anon-overlapping channel here in this context is a channel defined by theMAC/PHY protocol used by each of the WLANs identified in block 854 thatdoes not overlap with any of the 802.11 channels currently in use by theWLANs. The radio band of such non-overlapping channels also needs todefine a frequency range that encompasses any frequencies or radio bandsto be utilized by the WPTS for WPTS operation. This is a relativelystraightforward determination when the WLANs are implementing the same802.11 protocols, or otherwise 802.11 protocols that use the samechannels. However, when different 802.11 protocols are being used, thisdetermination may be more complicated, since the channels defined forsome of the 802.11 protocols differ, as shown above in FIGS. 10A-10C,for example.

If there is one or more non-overlapping channels available, the answerto decision block 856 will be YES, and the logic will proceed to a block858 in which the WPTS transmitter and clients will be operated using anavailable non-overlapping channel. As illustrated, in some embodimentsthe WPTS may periodically check (e.g., via polling ED measurements) todetect any changes in the shared wireless medium environment, such as anaddition or removal of a WLAN.

If there are no non-overlapping channels available, then the WPTS willutilize a channel being used by one of the WLANs sharing the wirelessenvironment as a co-channel. In a block 860, the WPTS selects theco-channel to be used for WPTS operations. Next in a decision block 861,a determination is made to whether there are any legacy stations(802.11a, 802.11b) operating in the WLAN using the co-channel. Asdiscussed above, if a WLAN has any legacy stations, it will beimplementing a CSMS/CA scheme using the RTS/CTS protocol. Since theRTS/CTS protocol adds overhead and reduces throughput, in one embodimentthe selection of the co-channel in block 860 may take this intoconsideration when there are other co-channels that could be selectedthat do not require support for legacy stations.

If the WLAN that will be sharing the selected co-channel does not haveany legacy stations, the logic proceeds to an optional decision block862 in which a determination is made to whether RTS/CTS is to beselectively used (although not required). There may be situations wherethe location of the WLAN stations and the location of the WPTStransmitter and WPTS clients are such that it may be advantageous to useRTS/CTS. In some embodiments, this determination may be made with theassistance of ED measurement made by one or more WPTS clients inaddition to WPTS measurements made by the WPTS transmitter.

IF no RTS/CTS is to be used, the logic proceeds to a block 864 in whichthe WPTS transmitter is operated as an emulated WLAN access point usingthe applicable 802.11 MAC and PHY protocols for access purposes to theco-channel shared with the WLAN. From the perspective of any 802.11devices (APs and stations) operating within the shared wireless mediumenvironment, the WPTS appears to be another WLAN AP that is implementingthe same 802.11 version as used by the co-channel WLAN. However, theWPTS doesn't perform full WLAN AP functionality, but rather only isimplementing aspects of a WLAN AP used to gain access to the co-channel.

These aspects include the following. In a block 866, the WPTStransmitter uses the applicable 802.11 CSMA/CA CDF protocol to selecttime slots to be uses as WPTS time slots. As discussed above, the CDFprotocol provides random access to the shared co-channel, under whichtime slots are (effectively) opportunistically selected for subsequenttransmission. In a block 868, the WPTS then uses the time slots it hasselected using the CDF protocol for WPTS operations, which as discussedabove, may involve one or more of transmitting power signals,transmitting data to WPTS clients, and receiving data transmitted byWPTS clients. As further shown, the operations of blocks 866 and 868 arerepeated on an ongoing basis.

Returning to decision blocks 861 and 862, if the answer to either ofthese is YES, the logic proceeds to a block 870 in which the WPTStransmitter is operated as an actual or emulated WLAN station within theWLAN sharing the co-channel, again using the applicable 802.11 MAC andPHY protocols for channel access purposes. Since the RTS/CTS protocolinvolves communication between a WLAN AP and station to reserve a timeslot, it is necessary for the WPTS transmitter to operate as a WLANstation if RTS/CTS is to be used. Accordingly, in a block 872, the WPTSregisters with the WLAN AP as a WLAN station using a real or pseudo MACaddress. Generally, every 802.11 device (AP or station) will include asix-octet MAC address that is guaranteed to be unique by themanufacturer of the device or the manufacturer of the radio subsystemused by the device. The MAC address is used for routing traffic withinthe WLAN, as well as for managing access to the channel. For emulated802.11 devices, the device may or may not have a “real” MAC address,depending on the implementation. However, from the viewpoint of the WLANAP, it is agnostic to whether a MAC address is a real address or apseudo address, as long as the MAC address is unique within the WLAN.

In a block 874 the WPTS transmitter uses the 802.11 CSMA/CA RTS/CTSprotocol to reserve time slots to be used as WPTS time slots. The WPTSthen uses the reserved time slots for WPTS operations in a block 876.The operations of blocks 874 and 876 are then repeated in an ongoingmanner.

To facilitate operation of the WPTS as an 802.11 WLAN access point orstation while using the WPTS time slots for WPTS operations,corresponding logic and components are added to the WPTS architecture,as shown in the block diagram of FIG. 3A. An 802.11 AP/Station WPTSoperation block 370 is added to control logic 310. This logic block isused for controlling the operation of the WPTS under which the WPTSfunctions as an 802.11 WLAN AP or WLAN station in the manner describedabove. Optionally, block 370 may be configured to only support operationof the WPTS as a WLAN AP or station (but not both).

Communication block 330 is depicted to further include an 802.11 PHYblock 372, which is used to facilitate 802.11 operations at the physicallayer. An 802.11 MAC block 374 may be implemented as part ofcommunication block 330 or as part of an 802.11 AP/Station WPTSoperation block 370, depending if the MAC layer is implemented inhardware or in software/firmware, or otherwise in embedded logic that isprogrammable. Communication block 330 also is depicted as including anoptional ZigBee™ block 376 and an optional Bluetooth™ block 378.

Generally, PHY block 372 may be implemented via a PHY chip (when MACblock 374 is implemented separately), or PHY block 732 and MAC block 734may be implemented on a MAC/PHY chip available from variousmanufactures, such as Broadcom, Cypress Semiconductor, Qualcomm, etc.Single chip MAC/PHY/Radio System on a Chip (SoC) components may also beused. Such SoC chips may also provide additional functionality, such asintegrated Bluetooth™, and include integrated transmitter amplifiers andreceiver circuitry. A customized chip may also be used, such as anMAC/PHY/Radio SoC that includes integrated ZigBee™.

WLAN Topology Discovery

In some instances, the WLAN topology of the shared wireless mediaenvironments in which a WPTS is implemented can be ascertained by theWPTS itself. FIG. 19 depicts a shared wireless media environment 1900having such a WLAN topology. Shared wireless media environment includesa WPTS 1902 and three WLAN access points 1904, 1906, and 1908. Each ofthese WLAN access points is the access point for an associated WLAN,labeled WLAN A, B, and C. FIG. 19 shows a respective circle 1910A,1910B, and 1910C representing the coverage areas of WLANs A, B, and C.The coverage area for a WLAN corresponds to the area in which the signalstrength from the WLAN's access point is sufficient to meet theapplicable 802.11 PHY requirements. For simplicity, the coverage areasare shown as circles; in reality, the shape of the coverage area for agiven WLAN will vary, depending on the physical environment in which theWLAN is deployed.

FIG. 19 also shows a WPTS coverage area 1912, which again is shown as acircle for simplicity. As with WLANs, the coverage area for a WPTS willvary depending on the physical environment in which the WPTS isdeployed. It is further noted that WPTS coverage area 1912 is depictedas having a nominal range from WPTS 1902. In practice, the WPTS coveragearea may be adjusted by changing the power level of the WPTS wirelesspower signals.

As discussed above, the IEEE 802.11 WLAN protocols define a number ofchannels under which the WLAN may operate. When a new WLAN is added to agiven environment, testing may reveal that there is interference on agiven channel. Accordingly, the WLAN AP may be configured to operate onanother channel. In the WLAN topology depicted in FIG. 19, the coverageareas 1910A, 1910B, and 1910C overlap, which may lead to interferenceissues if two or more of the WLANs were operating on the same channel.In this exemplary WLAN topology, WLAN A has been configured to operateon channel 1, while WLAN B utilizes channel 6 and WLAN C utilizeschannel 11. In addition, each of WLANs B and C are labeled as802.11n-2.4 networks, while WLAN A is being operated as an 802.11b,gnetwork. As will be recognized by those skilled in the art, many 802.11naccess points can service stations using other 802.11 versions, such as802.11 b and g.

Each WLAN is further depicted as including multiple stations comprisingmobile phones 1914, tablets 1916, and laptops 1918. The letters ‘A’,‘B’, and ‘C’ on mobile phones 1914, tablets 1916, and laptops 1918represent the WLAN each of these devices is associated with. Mobilephone 1920, which is depicted in gray, is a legacy device that can onlysupport 802.11b signaling. Since a legacy device is being serviced byWLAN B access point 1906, WLAN A utilizes the 802.11 RTC/CTS protocol.Meanwhile, WLANs B and C utilize the 802.11 CSMA/CA CDF protocol.

The devices shown in black are WPTS clients. These WPTS client areconfigured to utilize wireless power signals transmitted by WPTS 1902,and are further configured to communicate with WPTS 1902 using one ormore of an 802.11 protocol, ZigBee™, and Bluetooth™. WPTS 1902 isfurther configured to selectively transmit wireless power signals in thefrequency range of 2.4-2.45 GHz, including transmitting using a singlefrequency or radio band within the radio band of a given 802.11 channel.

For simplicity and point of illustration, it is presumed in this examplethat the WLAN access points and the WPTS cannot “hear” transmissionsbeyond their respective coverage areas. In practice, the 802.11 radiochips used by 802.11 APs and stations may be configured to ignore anysignals transmitted from other wireless devices (stations and APs)having a detected single strength below a threshold (e.g., the EDthresholds discussed above). As further depicted by areception/transmission area 1922 corresponding to a mobile phone 1924,each WLAN station will have its own reception and transmission area.

With this in mind, it is observed that WPTS 1902 can “see” access points1904 and 1908 for WLANs A and C, but cannot see WLAN B access point 1906(i.e., doesn't detect transmissions from AP 1906. Thus, WPTS 1902 cannotuse AP 1906 to determine what channel WLAN B is using (channel 6 in thisexample). As a result, WPTS 1902 might choose to use channel 6, sincechannel 6 is known to not interfere with channels 1 and 11. However,this may result in interference issues for any devices within thecoverage area 1912 of the WPTS that are WLAN B stations (depicted with‘B’). In some embodiments, the channel determination for WLAN B may beobtained by listening to one or more WLAN B stations within coveragearea 1912. However, there may be situations where the coverage area ofthe WPTS and the reception/transmission area of a WLAN station that isnot also a WPTS client differ such that the WPTS cannot hear such a WLANstation.

One of the management frames defined for 802.11 WLANs is a beacon frame,which contains information about the WLAN, including an SSID, supportedrates, Frequency-hopping (FH) Parameter Set, Direct-Sequence (DS)Parameter Set, Contention-Free (CF) Parameter Set, MSS Parameter Set,and a Traffic indication map (TIM). Beacon frames are periodicallytransmitted from the WLAN's AP, and may be listened to by devices withinthe coverage area of the AP. For WLAN APs a WPTS can hear, the WLANbeacon frames can be used to obtain information about the WLAN'soperational parameters.

Under some embodiments, a WPTS client may be configured to assist withWLAN topology discovery. For example, mobile phone 1926 is both a WLAN Bstation and a WPTS client, and can communicate with both WPTS 1902 andWLAN B AP 1906. Mobile WPTS client logic in mobile phone 1926 may beconfigured to access WLAN topology information from WLAN B AP 1906,thereby enabling WPTS 1902 to be apprised of WLAN B stations that itotherwise cannot detect by for which WPTS transmission may causeinterference.

Under some embodiments, the Control and Provisioning of Wireless AccessPoints (CAPWAP) Protocol Specification defined by RFC 5415 may be usedby the WPTS to communicate with the WLAN AP when the WPTS is operatingas an actual or emulated WLAN AP. Alternatively, the WPTS maycommunicate with an Access Controller (AC) that is used to manage acollection of Wireless Termination Points (WTPs, which is what some WLANAPs are referred in the specification.

Under some shared wireless medium environment topologies, the coveragearea of a WPTS and a particular WLAN may overlap, but there may not beany WLAN stations for that particular WLAN within that coverage area.Additionally, under some embodiments, a WPTS and a WLAN AP may beco-located (as separate systems), or a WPTS may be configured to supportfull WLAN AP functionality, including routing functionality andconnection to a wired network. In these cases, a wireless device that iswithin the coverage area of the WPTS/AP or co-located AP and within thecoverage area of another WLAN may select to not join the other WLAN.

As a result, coexisting operations of the WPTS and the other WLAN may besupported using the same channel (or one or more frequencies within thechannel) under which the channel is not shared. Since there are notstations for the other WLAN within the coverage area of the WPTS,transmission of WPTS power signals on the channel (or within thechannel) will not interfere with any of the other WLAN's stations.

Returning to FIG. 19, each of WLANs A, B, and C include WLAN stationswithin WPTS coverage area 1912. Since WPTS can only transmit wirelesspower signals using frequencies up to 2.45 GHz, WPTS cannot use channel14. Thus, WPTS will select one of WLANs A, B, or C to operate as aco-channel network with. This decision (which WLAN to choose) may bebased on various considerations, such as how many WPTS clients are beingoperated as stations in a particular WLAN, how many stations areoperating within each WLAN, and operational parameters of the WLANs. Insome embodiments it may be preferable to select a WLAN that does notneed to support legacy devices (and thus using RTS/CTS). In someembodiments, it may be preferable to select a WLAN with the least(current) utilization, since the fair sharing schemes would result inmore of the channel time slots being used as WPTS timeslots. Tofacilitate the determination of how many stations are present in eachWLAN, under some environments WLAN APs may be configured to communicatewith one another using a distributed management protocol under which theWLANs exchange topography information.

Opportunistic RTS/CTS Operation

The WPTS may be configured to implement an opportunistic RTS/CTSoperation to utilize more of the channel (when viewed from a time basis)than conventional RTS/CTS operation, while still operating in a mannerthat coexists with the WLAN. As discussed above, under RTS/CTS a stationrequesting access to the channel sends an RTS frame. This is followed bya CTS frame that is returned to the station that sent the RTS frame. TheCTS frame has a MAC header that includes a 2 octet duration value inmicroseconds.

The WPTS can take advantage of the following scenario. Under someembodiments the WPTS can use ED to detect the signal strength of thestation sending the RTS frame. If that signal strength falls below athreshold, such as the ED threshold defined for the 802.11 version beingused in the WLAN, then the WPTS may transmit power signals during thesame period defined by the duration in the CTS returned to therequesting station (the time slot reserved by the requestingstation)—that is the station receiving the CTS and the WPTS may transmitat the same time during the reserved time slot since the transmittedpower signals from the WPTS will not interfere with the requestingstations transmissions. Alternatively, if the WPTS cannot “hear” a CTS(e.g., under a standard PHY configuration for the applicable 802.11version), but can “hear” a RTS, the WPTS can transmit power signalsduring the time slot reserved by the requesting station. Under thislatter approach, a separate ED threshold detection is not needed, as thePHY will be configured to ignore any communications that fall below apredefined sensitivity level.

As situation under which the WPTS will not be able to detect RTS frames,but will be able to detect CTS frames is illustrated in FIG. 19. Forexample, WPTS 1902 will not be able to detect CTS frames transmittedfrom any of the WLAN stations in WLAN A that are outside of WPTScoverage area 1912, but will be able to detect all of the CTS framessince WLAN A AP 1904 is within WPTS coverage area 1912.

In some embodiments, a WPTS may utilize multiple co-channels, or use acombination co-channel and opportunistic RTS/CTS scheme. For example,under share wireless medium environment 1900, WPTS 1902 may utilizeeither channel 6 or channel 11 for co-channel operation with WLAN B orWLAN C, while listening to the RTS and CTS frames transmitted in WLAN A,and using channel 1 for time slots that are detected as being reservedby WLAN A stations that are outside of WPTS coverage area 1912.

Sharing Access to Wireless Medium Using Devices with Multiple PHYs

In accordance with further aspects of some embodiments, techniques areprovided for devices with multiple PHYs to access shared wireless mediumenvironments under which a first PHY and associated MAC is used toselect or reserve time slots, while a second PHY is used to transmitand/or receive signals during those time slots. An exemplary embodimentillustrating such a device and how it is implemented is shown in diagram2000 of FIG. 20.

A multi-PHY host device 2002 includes a single or multiple-mode PHY 2004(also labeled and referred to as PHY 1) and a separate PHY 2006 (alsoreferred labeled and referred to as PHY 2). A MAC 2008 is depicted abovePHY 1 and the dashed outline 2010 indicates that PHY 1 and MAC 2008 maybe implemented on the same chip, such as the same radio subsystem chip.Meanwhile, a MAC 2012 depicted above PHY 2 is shown as a dashed block toindicate it is optional. For simplicity other aspects of the PHY andmulti-PHY host device 2002 are not shown such as transmit and receiveamplifiers and antennae.

The left-hand side of diagram 2000 depicts operations performed by PHY 1and MAC 2008. These operations begin at a start block 2014. In a block2016, the presence of one of more WLANs operating in the shared wirelessmedium are detected. This can generally be performed using thetechniques described above with reference to FIGS. 8A and 8B. Under theillustrated scheme, PHY 1 is a single or multi-mode PHY, meaning it maybe configured to implement a single PHY or multiple PHYs. For example,in the context of IEEE 802.11, a single PHY might be any of 802.11a,802.11b, 802.11g, 802.11n, and 802.11 ac. In the case of a multi-modePHY, the PHY supports multiple different PHYs (referred to as PHY modes)under which the signaling used by the different PHYs is different. Forexample, 802.11b uses DSSS, while 802.11a and 802.11g uses OFDM and802.11n and 802-11ac use MIMO-OFDM.

In the case of a multi-mode PHY, PHY 1 will scan the available channelsfor one or more of its PHY modes to detect the presence of a WLANutilize that channel and a PHY corresponding to the PHY mode. This isdepicted by start and end loop blocks 2018 and 2022, and a decisionblock 2020. When a PHY and channel is detected to be in use in decisionblock 2020, that PHY and channel is added to a list of WLANs operatingin the shared wireless medium environment.

Upon completion of block 2016, the logic proceeds to a block 2024 inwhich a channel and PHY/MAC protocol(s) to be used to access the sharedwireless medium are identified. For example, suppose channel 1 of anIEEE 802.11g WLAN is to be used. The PHY and MAC protocols will be thecorresponding PHY and MAC protocols defined by the IEEE 802.11g WLANspecification. It is noted that the embodiment of FIG. 20 is not limitedto IEEE 802.11 WLANs, but rather may be implemented in a shared wirelessmedium environment in which one or more WLANs using any existing orfuture WLAN standard are operating. In some embodiments, the PHY/MAC isconsidered to be a single protocol that covers both the operation of thePHY Layer and the MAC Layer.

In a block 2026 the PHY/MAC protocol(s) are used to select and/orreserve time slots to access the shared wireless medium. For IEEE 802.11WLANs, this can be done in the manner discussed above, e.g., usingCSMA-CA with a CFD algorithm to select time slots or using an RTS/CTSscheme to reserve time slots. For other types of existing and futureWLANs, appropriate techniques for selecting and/or reserving time slots(as applicable) may be used. As shown by the loop back to itself, theoperations of block 2026 are performed on an ongoing basis.

The right-hand side of diagram 2000 depicts utilization of PHY 2 toaccess the shared wireless medium. PHY 2 is going to be using adifferent PHY than PHY 1. For example, in some embodiments, PHY 1 willbe an IEEE 802.11 PHY, while PHY 2 will be a non-IEEE 802.11 PHY. Insome embodiments, the frequency or radio band used by PHY 2 will overlapthe radio band of the channel used by PHY 1, as illustrated in FIG. 21below.

As illustrated, PHY 2 will access the shared wireless medium at timeslots 2028, 2030, and 2032, which were selected and/or reserved usingPHY 1 and an associated MAC in block 2026. During time periods 2034,2036, and 2038 PHY 2 will not transmit signals, although in someembodiments it may receive signals transmitted by other devices (notshown) using PHY 2. During the access time slots 2028, 2030, and 2032,PHY 2 may be used to transmit and/or receive signals. As discussedabove, in some embodiments, PHY 2 may employ MAC 2012 during these timeslots. Optionally, under other embodiments a MAC is not used.

FIG. 20 illustrated three examples of “overlapping” as used herein,including the claims. PHY-1 uses the same channel diagram as illustratedin FIG. 9A, which illustrates the channel spacing of an 802.11b and802.11g WLAN operating at 2.4 GHz. PHY-2 is depicted that has a radioband having a width of 10 MHz that is entirely contained within the 22MHz radio band of channel 1. PHY-3 is depicted to have a 10 MHz radioband that partially overlaps channel 11. PHY-4 uses a single 2.470 MHzfrequency that is within the radio band of channel 11. Similaroverlapping may be implemented for other WLANs. It is further noted thatthe 10 MHz radio band width is exemplary, as a given PHY may implementradio bands having different bandwidths.

Exemplary Wireless Power Receiver Client (WPTS Client)

FIG. 22 depicts a block diagram illustrating example components of arepresentative mobile device or tablet computer 2200 with a wirelesspower receiver or client in the form of a mobile (or smart) phone ortablet computer device, according to an embodiment. Various interfacesand modules are shown with reference to FIG. 22, however, the mobiledevice or tablet computer does not require all of the modules orfunctions for performing the functionality described herein. It isappreciated that, in many embodiments, various components are notincluded and/or necessary for operation of the category controller. Forexample, components such as GPS radios, cellular radios, andaccelerometers may not be included in the controllers to reduce costsand/or complexity. Additionally, components such as ZigBee™ radios andRFID transceivers, along with antennas, can populate the Printed CircuitBoard.

The wireless power receiver client can be a power receiver client 103 ofFIG. 1, although alternative configurations are possible. Additionally,the wireless power receiver client can include one or more RF antennasfor reception of power and/or data signals from a power transmissionsystem, e.g., wireless power transmission system 101 of FIG. 1.

FIG. 23 depicts a diagrammatic representation of a machine, in theexample form, of a computer system within which a set of instructions,for causing the machine to perform any one or more of the methodologiesdiscussed herein, may be executed.

In the example of FIG. 23, the computer system includes a processor,memory, non-volatile memory, and an interface device. Various commoncomponents (e.g., cache memory) are omitted for illustrative simplicity.The computer system 2300 is intended to illustrate a hardware device onwhich any of the components depicted in the example of FIG. 1 (and anyother components described in this specification) can be implemented.For example, the computer system can be any radiating object or antennaarray system. The computer system can be of any applicable known orconvenient type. The components of the computer system can be coupledtogether via an interconnect, such as a PCIe (Peripheral ComponentInterconnect Express) interconnect. For simplicity, a singleinterconnect is shown in FIG. 23; in practice an interconnect hierarchymay be used, as will be recognized by those skilled in the computerarts.

The processor may be, for example, a conventional microprocessor such asan Intel® or AMD® microprocessor or an ARM-based microprocessor. Thoseskilled in the computer arts will recognize that the terms“machine-readable (storage) medium” or “computer-readable (storage)medium” generally include any type of device that can store instructionsand or data that is accessible by the processor.

The memory is coupled to the processor by, for example, one or morememory channels connecting the memory to a memory controller in theprocessor (not shown). The memory can include, by way of example but notlimitation, random access memory (RAM), such as dynamic RAM (DRAM) andstatic RAM (SRAM).

The interconnect or interconnect hierarchy also couples the processor tothe non-volatile memory and drive unit. The non-volatile memory and/ordrive unit may generally be any device capable of storing data in anon-volatile manner, such as a solid state drive (SSD), amagnetic-optical disk, an optical disk, a read-only memory (ROM), anEPROM, or EEPROM, a magnetic or optical card, or a Flash memory device.

Software is typically stored in the non-volatile memory and/or the driveunit and loaded into volatile memory (e.g., RAM) prior to execution.Indeed, for large programs, it may not be possible to store the entireprogram in the memory. Nevertheless, it should be understood that forsoftware to run, if necessary, it is moved to a computer readablelocation appropriate for processing, and for illustrative purposes, thatlocation is referred to as the memory herein. Even when software ismoved to the memory for execution, the processor will typically make useof hardware registers to store values associated with the software, andlocal cache that, ideally, serves to speed up execution. As used herein,a software program is assumed to be stored at any known or convenientlocation (from non-volatile storage to hardware registers) when thesoftware program is referred to as “implemented in a computer-readablemedium”. A processor is considered to be “configured to execute aprogram” when at least one value associated with the program is storedin a register readable by the processor.

The interconnect also couples the processor to the network interfacedevice. The interface can include one or more of a modem or networkinterface. It will be appreciated that a modem or network interface canbe considered to be part of the computer system. The interface caninclude an Ethernet interface or Network Interface Controller (NIC), anInfiniBand Host Channel Adaptor (HCA), an ISDN modem, a cable modem,token ring interface, a wireless network interface (e.g., IEEE 802.11radio), a satellite transmission interface, or other interfaces forcoupling a computer system to other computer systems. The interface caninclude one or more input and/or output devices. The I/O devices caninclude, by way of example but not limitation, a keyboard, a mouse orother pointing device, disk drives, printers, a scanner, and other inputand/or output devices, including a display device. The display devicecan include, by way of example but not limitation, a cathode ray tube(CRT), liquid crystal display (LCD), or some other applicable known orconvenient display device. For simplicity, it is assumed thatcontrollers of any devices not depicted in the example of FIG. 23 residein the interface.

In operation, the computer system 2300 can be controlled by operatingsystem software that includes a file management system, such as a diskoperating system. One example of operating system software withassociated file management system software is the family of operatingsystems known as Windows® from Microsoft Corporation of Redmond, Wash.,and their associated file management systems. Another example ofoperating system software with its associated file management systemsoftware is the Linux operating system and its associated filemanagement system. The file management system is typically stored in thenon-volatile memory and/or drive unit and causes the processor toexecute the various acts required by the operating system to input andoutput data and to store data in the memory, including storing files onthe non-volatile memory and/or drive unit.

Some portions of the detailed description may be presented in terms ofalgorithms and symbolic representations of operations on data bitswithin a computer memory. These algorithmic descriptions andrepresentations are the means used by those skilled in the dataprocessing arts to most effectively convey the substance of their workto others skilled in the art. An algorithm is here, and generally,conceived to be a self-consistent sequence of operations leading to adesired result. The operations are those requiring physicalmanipulations of physical quantities. Usually, though not necessarily,these quantities take the form of electrical or magnetic signals capableof being stored, transferred, combined, compared, and otherwisemanipulated. It has proven convenient at times, principally for reasonsof common usage, to refer to these signals as bits, values, elements,symbols, characters, terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise, as apparent from the followingdiscussion, it is appreciated that throughout the description,discussions utilizing terms such as “processing” or “computing” or“calculating” or “determining” or “displaying” or the like, refer to theaction and processes of a computer system, or similar electroniccomputing device, that manipulates and transforms data represented asphysical (electronic) quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission or display devices.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various general purposesystems may be used with programs in accordance with the teachingsherein, or it may prove convenient to construct more specializedapparatus to perform the methods of some embodiments. The requiredstructure for a variety of these systems will appear from thedescription below. In addition, the techniques are not described withreference to any particular programming language, and variousembodiments may thus be implemented using a variety of programminglanguages.

In alternative embodiments, the machine operates as a standalone deviceor may be connected (e.g., networked) to other machines. In a networkeddeployment, the machine may operate in the capacity of a server or aclient machine in a client-server network environment or as a peermachine in a peer-to-peer (or distributed) network environment.

The machine may be a server computer, a client computer, a personalcomputer (PC), a tablet PC, a laptop computer, a set-top box (STB), apersonal digital assistant (PDA), a cellular telephone, an iPhone, aBlackberry, a processor, a telephone, a web appliance, a network router,switch or bridge, or any machine capable of executing a set ofinstructions (sequential or otherwise) that specify actions to be takenby that machine.

While the machine-readable medium or machine-readable storage medium isshown in an exemplary embodiment to be a single medium, the term“machine-readable medium” and “machine-readable storage medium” shouldbe taken to include a single medium or multiple media (e.g., acentralized or distributed database, and/or associated caches andservers) that store the one or more sets of instructions. The term“machine-readable medium” and “machine-readable storage medium” shallalso be taken to include any medium that is capable of storing, encodingor carrying a set of instructions for execution by the machine and thatcause the machine to perform any one or more of the methodologies of thepresently disclosed technique and innovation.

In general, the routines executed to implement the embodiments of thedisclosure, may be implemented as part of an operating system or aspecific application, component, program, object, module or sequence ofinstructions referred to as “computer programs.” The computer programstypically comprise one or more instructions set at various times invarious memory and storage devices in a computer, and that, when readand executed by one or more processing units or processors in acomputer, cause the computer to perform operations to execute elementsinvolving the various aspects of the disclosure.

Moreover, while embodiments have been described in the context of fullyfunctioning computers and computer systems, those skilled in the artwill appreciate that the various embodiments are capable of beingdistributed as a program product in a variety of forms, and that thedisclosure applies equally regardless of the particular type of machineor computer-readable media used to actually effect the distribution.

Further examples of machine-readable storage media, machine-readablemedia, or computer-readable (storage) media include but are not limitedto recordable type media such as volatile and non-volatile memorydevices, floppy and other removable disks, hard disk drives, opticaldisks (e.g., Compact Disk Read-Only Memory (CD ROMS), Digital VersatileDisks, (DVDs), etc.), among others, and transmission type media such asdigital and analog communication links.

In general, the circuitry, logic and components depicted in the figuresherein may also be implemented in various types of integrated circuits(e.g., semiconductor chips) and modules, including discrete chips, SoCs,multi-chip modules, and networking/link interface chips includingsupport for multiple network interfaces. Also, as used herein, circuitryand logic to effect various operations may be implemented via one ormore of embedded logic, embedded processors, controllers, microengines,or otherwise using any combination of hardware, software, and/orfirmware. For example, the operations depicted by various logic blocksand/or circuitry may be effected using programmed logic gates and thelike, including but not limited to ASICs, FPGAs, IP block libraries, orthrough one or more of software or firmware instructions executed on oneor more processing elements including processors, processor cores,controllers, microcontrollers, microengines, etc.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” As used herein, the terms “connected,”“coupled,” or any variant thereof, means any connection or coupling,either direct or indirect, between two or more elements; the coupling ofconnection between the elements can be physical, logical, or acombination thereof. Additionally, the words “herein,” “above,” “below,”and words of similar import, when used in this application, shall referto this application as a whole and not to any particular portions ofthis application. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number respectively.

Not all components, features, structures, characteristics, etc.described and illustrated herein need be included in a particularembodiment or embodiments. If the specification states a component,feature, structure, or characteristic “may”, “might”, “can” or “could”be included, for example, that particular component, feature, structure,or characteristic is not required to be included. If the specificationor claim refers to “a” or “an” element, that does not mean there is onlyone of the element. If the specification or claims refer to “anadditional” element, that does not preclude there being more than one ofthe additional element.

The above detailed description of embodiments of the disclosure is notintended to be exhaustive or to limit the teachings to the precise formdisclosed above. While specific embodiments of, and examples for, thedisclosure are described above for illustrative purposes, variousequivalent modifications are possible within the scope of thedisclosure, as those skilled in the relevant art will recognize. Forexample, while processes or blocks are presented in a given order,alternative embodiments may perform routines having steps, or employsystems having blocks, in a different order, and some processes orblocks may be deleted, moved, added, subdivided, combined, and/ormodified to provide alternative or subcombinations. Each of theseprocesses or blocks may be implemented in a variety of different ways.Also, while processes or blocks are, at times, shown as being performedin a series, these processes or blocks may instead be performed inparallel, or may be performed at different times. Further, any specificnumbers noted herein are only examples: alternative implementations mayemploy differing values or ranges.

The teachings of the disclosure provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

Any patents and applications and other references noted above, includingany that may be listed in accompanying filing papers, are incorporatedherein by reference. Aspects of the disclosure can be modified, ifnecessary, to employ the systems, functions, and concepts of the variousreferences described above to provide yet further embodiments of thedisclosure.

These and other changes can be made to the disclosure in light of theabove Detailed Description. While the above description describescertain embodiments of the disclosure, and describes the best modecontemplated, no matter how detailed the above appears in text, theteachings can be practiced in many ways. Details of the system may varyconsiderably in its implementation details, while still beingencompassed by the subject matter disclosed herein. As noted above,particular terminology used when describing certain features or aspectsof the disclosure should not be taken to imply that the terminology isbeing redefined herein to be restricted to any specific characteristics,features, or aspects of the disclosure with which that terminology isassociated. In general, the terms used in the following claims shouldnot be construed to limit the disclosure to the specific embodimentsdisclosed in the specification, unless the above Detailed Descriptionsection explicitly defines such terms. Accordingly, the actual scope ofthe disclosure encompasses not only the disclosed embodiments, but alsoall equivalent ways of practicing or implementing the disclosure underthe claims.

While certain aspects of the disclosure are presented below in certainclaim forms, the inventors contemplate the various aspects of thedisclosure in any number of claim forms. For example, while only oneaspect of the disclosure is recited as a means-plus-function claim under35 U.S.C. § 112, ¶6, other aspects may likewise be embodied as ameans-plus-function claim, or in other forms, such as being embodied ina computer-readable medium. (Any claims intended to be treated under 35U.S.C. § 112, ¶6 will begin with the words “means for”.) Accordingly,the applicant reserves the right to add additional claims after filingthe application to pursue such additional claim forms for other aspectsof the disclosure.

The detailed description provided herein may be applied to othersystems, not necessarily only the system described above. The elementsand acts of the various examples described above can be combined toprovide further implementations of the invention. Some alternativeimplementations of the invention may include not only additionalelements to those implementations noted above, but also may includefewer elements. These and other changes can be made to the invention inlight of the above Detailed Description. While the above descriptiondefines certain examples of the invention, and describes the best modecontemplated, no matter how detailed the above appears in text, theinvention can be practiced in many ways. Details of the system may varyconsiderably in its specific implementation, while still beingencompassed by the invention disclosed herein. As noted above,particular terminology used when describing certain features or aspectsof the invention should not be taken to imply that the terminology isbeing redefined herein to be restricted to any specific characteristics,features, or aspects of the invention with which that terminology isassociated. In general, the terms used in the following claims shouldnot be construed to limit the invention to the specific examplesdisclosed in the specification, unless the above Detailed Descriptionsection explicitly defines such terms. Accordingly, the actual scope ofthe invention encompasses not only the disclosed examples, but also allequivalent ways of practicing or implementing the invention.

The above description of illustrated embodiments of the invention,including what is described in the Abstract, is not intended to beexhaustive or to limit the invention to the precise forms disclosed.While specific embodiments of, and examples for, the invention aredescribed herein for illustrative purposes, various equivalentmodifications are possible within the scope of the invention, as thoseskilled in the relevant art will recognize.

These modifications can be made to the invention in light of the abovedetailed description. The terms used in the following claims should notbe construed to limit the invention to the specific embodimentsdisclosed in the specification and the drawings. Rather, the scope ofthe invention is to be determined entirely by the following claims,which are to be construed in accordance with established doctrines ofclaim interpretation.

1. A method for delivering wireless power from a wireless powertransmission system (WPTS) to one or more wireless power receiverclients in a shared wireless medium environment including one or moreInstitute of Electrical and Electronics Engineers (IEEE) 802.11 wirelesslocal area networks (WLANs), comprising: operating the WPTS to coexistwith the operation of the one or more WLANs, wherein the WPTS transmitspower signals to the one or more wireless power receiver clients usingat least one frequency or channel that overlaps a channel utilized by atleast one of the one or more WLANs.
 2. The method of claim 1, furthercomprising: detecting, for each of at least one of the one or more IEEE802.11 WLANs, a channel being utilized by the WLAN; and one or more IEEE802.11 Media Access Channel (MAC) and Physical Layer (PHY) protocolsutilized by the WLAN; and identifying a channel to be implemented as aco-channel by the WPTS and an IEEE 802.11 MAC and PHY protocol to beimplemented by the WPTS.
 3. The method of claim 2, further comprising:utilizing the co-channel and IEEE 802.11 MAC and PHY protocol to selector reserve WPTS time slots during which the WPTS is to access the sharedwireless medium; and transmitting wireless power signals to the one ormore wireless power receiver clients during at least a portion of theWPTS time slots, wherein the wireless power signals employ at least onefrequency or channel that overlaps the co-channel.
 4. The method ofclaim 3, further comprising at least one of transmitting data to the oneor more wireless power receiver clients or receiving transmissions fromone or more wireless power receiver clients during at least a portion ofthe WPTS time slots.
 5. The method of claim 3, wherein the IEEE 802.11MAC protocol supports a carrier-sense multiple access with collisionavoidance (CSMA/CA) scheme employing a distributed coordinationfunction, and the WPTS is configured to implement the CSMA/CA scheme tosupport sharing of the co-channel.
 6. The method of claim 5, furthercomprising operating the WPTS as one of an IEEE 802.11 WLAN access pointor an emulated IEEE 802.11 WLAN access point under which the IEEE 802.11MAC and PHY protocols are implemented for managing access to the sharedwireless medium using the CSMA/CA scheme.
 7. The method of claim 1,further comprising: identifying a WLAN to share channel access with, theWLAN transmitting over a channel to be shared and implementing an IEEE802.11 Media Access Channel (MAC) protocol supporting a carrier-sensemultiple access with collision avoidance (CSMA/CA) scheme employing aRequest to Send and Clear to Send (RTS/CTS) algorithm to access theshared channel; and utilizing the IEEE 802.11 MAC protocol to reservetime slots during which the WPTS at least one of, transmits wirelesspower signals using at least one frequency or channel that overlaps theshared channel; and receives transmission from at least one of the oneor more wireless power receiver clients using at least one frequency orchannel that overlaps the shared channel.
 8. The method of claim 1,further comprising: detecting a change in utilization of the sharedwireless medium environment under which a channel that was being used byone of the one or more WLANs becomes available; and transmitting powersignals with the WPTS to the one or more wireless power receiver clientsusing at least one frequency within a radio band for the channel.
 9. Awireless power transmission system (WPTS) comprising: an antenna arrayhaving multiple radio frequency (RF) antennas; an Institute ofElectrical and Electronics Engineers (IEEE) 802.11 radio subsystemincluding at least one antenna; and control logic operatively coupled tothe antenna array and the (IEEE) 802.11 radio subsystem configured to:detect operation of one or more IEEE 802.11 wireless local area networks(WLANs) in a shared wireless medium environment including the WPTS, eachWLAN utilizing a respective channel; and operate the WPTS to coexistwith the operation of the one or more WLANs, wherein the WPTS transmitspower signals via the antenna array to the one or more wireless powerreceiver clients using at least one frequency or channel that overlaps achannel utilized by at least one of the one or more WLANs.
 10. Thewireless power transmission system of claim 9, wherein the control logicis further configured to: detect, for each of at least one of the one ormore IEEE 802.11 WLANs, a channel being utilized by the WLAN; one ormore IEEE 802.11 Media Access Channel (MAC) and Physical Layer (PHY)protocols utilized by the WLAN; and identify a channel to be implementedas a co-channel by the WPTS and an IEEE 802.11 MAC and PHY protocol tobe implemented by the WPTS.
 11. The wireless power transmission systemof claim 10, wherein the control logic is further configured to: utilizethe co-channel and IEEE 802.11 MAC and PHY protocol to select or reserveWPTS time slots during which the WPTS is to access the shared wirelessmedium; and transmit wireless power signals to the one or more wirelesspower receiver clients during at least a portion of the WPTS time slots,wherein the wireless power signals employ at least one frequency orchannel that overlaps the co-channel.
 12. The wireless powertransmission system of claim 11, wherein the control logic is furtherconfigured to at least one of transmit data to the one or more wirelesspower receiver clients or receive transmissions from one or morewireless power receiver clients during at least a portion of the WPTStime slots.
 13. The wireless power transmission system of claim 11,wherein the IEEE 802.11 MAC protocol supports a carrier-sense multipleaccess with collision avoidance (CSMA/CA) scheme employing a distributedcoordination function (DCF), and wherein the control logic is furtherconfigured to implement the CSMA/CA scheme to support sharing of theco-channel.
 14. The wireless power transmission system of claim 13,wherein the control logic is further configured to operate the WPTS asone of an IEEE 802.11 WLAN access point or an emulated IEEE 802.11 WLANaccess point under which the IEEE 802.11 MAC and PHY protocols areimplemented for managing access to the shared wireless medium using theCSMA/CA scheme.
 15. The wireless power transmission system of claim 9,wherein the control logic is further configured to: identify a WLANamong the one or more WLANs to share channel access with, the WLAN thatis identified transmitting over a channel to be shared and implementingan IEEE 802.11 Media Access Channel (MAC) protocol supporting acarrier-sense multiple access with collision avoidance (CSMA/CA) schemeemploying a Request to Send and Clear to Send (RTS/CTS) algorithm toaccess the shared channel; and utilize the IEEE 802.11 MAC protocol toreserve time slots during which the WPTS at least one of, transmitswireless power signals using at least one frequency or channel thatoverlaps the shared channel; and receives transmissions from at leastone of the one or more wireless power receiver clients using at leastone frequency or channel that overlaps the shared channel.
 16. Thewireless power transmission system of claim 9, wherein the control logicis further configured to: detect a change in utilization of the sharedwireless medium environment under which a channel that was being used byone of the one or more WLANs becomes available; and transmit powersignals with the WPTS to the one or more wireless power receiver clientsusing at least one frequency within a radio band for the channel.
 17. Awireless power transmission system (WPTS) comprising: an antenna arrayhaving multiple radio frequency (RF) antennas; means for detectingoperation of one or more wireless local area networks (WLANs) in ashared wireless medium environment including the WPTS, each WLANutilizing a respective channel; and control logic operatively coupled tothe antenna array and configured to operate the WPTS to coexist with theoperation of the one or more WLANs, wherein the WPTS transmits powersignals via the antenna array to the one or more wireless power receiverclients using at least one frequency or channel that overlaps a channelutilized by at least one of the one or more WLANs.
 18. The wirelesspower transmission system of claim 17, further comprising: means fordetecting, for each of at least one of the one or more WLANs, a channelbeing utilized by the WLAN; and one or more Media Access Channel (MAC)and Physical Layer (PHY) protocols utilized by the WLAN, and wherein thecontrol logic is further configured to identify a channel to beimplemented as a co-channel by the WPTS and a MAC and PHY protocol to beimplemented by the WPTS.
 19. The wireless power transmission system ofclaim 18, wherein the control logic is further configured to: utilizethe co-channel and the MAC and PHY protocol to select or reserve WPTStime slots during which the WPTS is to access the shared wirelessmedium; and transmit wireless power signals to the one or more wirelesspower receiver clients during at least a portion of the WPTS time slots,wherein the wireless power signals employ at least one frequency orchannel that overlaps the co-channel.
 20. The wireless powertransmission system of claim 19, wherein the MAC protocol supports acarrier-sense multiple access with collision avoidance (CSMA/CA) schemeemploying a distributed coordination function (DCF), and wherein thecontrol logic is further configured to implement the CSMA/CA scheme tosupport sharing of the co-channel.